The more large segments you share, the more closely related you are to a DNA match. To learn more about segments, read the blog by one of my favorite DNA writers on the yahoo DNA-NEWBIE list, Jim Bartlett, called Segmentology.org
He explains why you share such large chunks of DNA with your closer relatives by showing how recombination works and how few cross-overs there usually are in a recent post at http://segmentology.org/2015/05/24/segments-bottom-up/
While the total amount of shared DNA in centimorgans (cMs) is a fine indicator for your closest relatives out to second cousins, farther relationships can be more and more random in the amount of shared DNA. You can consult the charts and numbers at ISOGG here – http://www.isogg.org/wiki/Autosomal_DNA_statistics – to determine those closer relatives.
Although I like this new chart from Blaine Bettinger the best:
[UPDATE 16 May 2018: I now recommend the DNApainter calculator based on Blaine’s work shown above and Leah Larkin and Andrew Millard’s calculations at https://dnapainter.com/tools/sharedcmv4 ]
Note that since you share about 25% with an aunt, uncle, grandparent, grandchild or half sibling the amount shared cannot tell those relatives apart [UPDATE 20 Oct 2017: See my study results showing that paternal half siblings can be told from the others here http://blog.kittycooper.com/2017/09/the-25-relationship-a-first-look-at-the-data/ ]. Sometimes the X can help distinguish those, see my post on that here.
Frankly the testing companies are not that accurate in predicting your more distant relationships, those past 2nd cousins. So when deciding which DNA matches to pursue, follow up on the ones with more than one large segment; those are your closer relatives, the ones whose trees may be easier to connect to yours.
With my two successful matches, or matches with whom I found a connection, I know how unpredictable the size can be. And recently, after having a lot of cousins tested and two of them are 2nd cousins to each other and they share the largest segment 40.4cM, total 157cM, to me was a good indicator on what 2nd cousins should be sharing, more or less. Since I get pages and pages of 2nd cousins, if not predicted closer (FTDNA), it was good to go by this.
My mother has had a 50cM largest segment match (total 122cM) and knew that this had to have been a close match. Took me over 7 months to figure that out (actually 11 straight days of non-stop research) to find out that my mother and this match are 1/2 third cousins. Pretty distant in a way, but that 50cM is pretty large. The next largest segment is 38cM.
My mother gave my brother basically that same largest segment whereas I got only 14cM of that same exact segment. I actually share 28cM of that 2nd largest segment, but had I not got my mother DNA tested (I tested first) I wouldn’t have paid attention to that match, and actually I didn’t until almost a year after my mother tested.
Definitely from 2nd cousins on it can be unpredictable.
Very interesting, I am new to Genetic Genealogy, I have been researching my ancestry for a long time, but I am going in circles on one DNA match. I definitely feel having my cousins test themselves and adding their DNA is a great way to discount possibilities.
My dad’s first cousin has a 688cM across 37 segments match to me. This is very high. Always felt I was strongly linked to my dad’s side.
I have 4 sisters from an unknown family who link with me ranging from 46cM-31cMand a shared link with us who shares 110cM’s over 7 Segments with me. They cannot link this person, I cannot yet link this person.
We can’t find any common link, but I have no idea who my nan’s father could be. I do know the closer of these links had relatives in the correct Geographical Area in the correct year for my nan’s birth, but that could be wishful thinking!!
Time and more relatives testing will tell!
Yes test as many relatives as you can, particularly older ones. That 688 is high but within range.
The 31-46 group is low, anything from a 4th-8th or even further. I tend to work only on matches of 100cm or more to start with as the others are often too far back to find.
Who is your “nan”? your grandmother? There are good techniques for finding unlnown parents/grandparents with DNA see this page for some resources:
Hi, I would be interested to hear if you have made any progress on this- I also have a 1st cousin of my dad with a match in the range you indicate- we share 698 cM and 32 segments.
And even 2nd cousins can be highly variable. In my own family we share twice the DNA with a second cousin on Dad’s maternal side as with one on his paternal side
Kitty, a great post – and thanks for the plug. My true brother and I have such a mish-mash of DNA, that the Admixture/Ethnicity programs look like we are not related! DNA is random and very variable.
Kitty – Great post. I’m so glad you like the chart! I’m still working on the Shared cM Project, there’s so much still to do, stay tuned!
And I agree, Jim’s blog must be added to everyone’s must-read list!
I am trying to understand the significance between “Total Segments” and “Largest Segments” on Gedmatch. If you have let’s say, 8 matching segments with someone, and the largest segment is maybe 4 or 5cM, and the total of all segments is maybe 17cM, is that of significance when trying to find a common ancestor down the line? I guess I’m confused with terminology because I keep reading in many places that matches over 10cM are pretty good ones, but I don’t know if this means 10cm on one segment alone or a total of multiple segments.
In your example the segments are too small for the relationship to likely be findable.
If there is no endogamy in your tree then anyone who matches you on multiple segments of 7cM or larger is worth following up on. Segments smaller than that are often false, below 5cM they are false more often than true.
Use total cM of 7cM and larger segments with the charts above which you can get on the one to one compare
Kitty, thanks so much for giving me a better insight on this. So basically if I match with someone and all we share is just one segment well under 7cM, it is highly probable of being a false positive, but if I match someone and we have several segments that come to an overall total over 7cM, that person would be worthy of further investigation. Did I get that right?
Almost right. It is not the overall total that is 7cM or larger but the largest segment that should be greater than 7cM and preferable at least one other segment close to that size. Read this blog post of mine for some more insight
Start with the folk who share the most DNA with you
Gotcha! Thanks again for the help!
Hi, you seem to know so much . Can i ask you, i just found out a woman is a 745cm across 40 segments to me. Could she be an aunt? She told me she was adopted and does not know who her real father is?
That is too low for an Aunt. Use this calculator to see the possibilies
Most likely a first cousin then her father is a sibling of one of your parents. How big is the age difference? Does she match cousins of yours as well? Which side? have her read this
I am more or less the kit Admin for my adopted Japanese daughter in law. I noticed two of her matches, a mother and daughter have a lot of small segments. The mother daughter pair are probably 3c1r and 4th cousin. The daughter has the most looking at 3cm she has 130 cM total, other 4th cousins have maybe 30 to 40 cM some a little more. Does this mean anything? I was thinking maybe they are a little closer than they appear?
Small segments can be population specific. We tend to only look at matching segments greater than 7cM and total those. Also large segments greater than 20cM are indicative of a closer relationship not lots of little segments.
Look at the numbers here after you total the larger segments.
Also if the daughter has matching segments that the mother does not, they would come from her father. Matching on both sides like that can make a relationship look closer than it is.
Love all of your data, i am just getting my 23andme results back and trying to reach out to some of my “Closest” cousins haha. I am talking to one that i match two segments on the X chromosome at 22CM and 9CM i assume i should definitely pursue research there right? I mean we only share .45% DNA, but having two over 7CM on the same Chromosome matters right? SOrry, i am new
Yes two good sized segments on the X matters, especially with one so large and you being male. If there is no other matching segments, then likely a 4th/5th cousin… The X is a little different, it can last a long time and men only get X from their mother …
Thank you so much! I love this site, gonna buy you a glass of wine here soon. 🙂
Sorry for the follow up, does that mean this person (a female) is related to me on my mothers side for sure, since its ONLY the X ?
Yes, your mother’s side, either side for her
Ok great, thanks! GEDmatch is awesome!
A match recently reached out to me because it appeared we were closer than we actually are. We match at 18.5 cM on 2 segments, but it was when I looked at the chromosomes with my dad and brother that I realized I shared one segment on chromosome 6 with her through my dad (which was the same amount of 11.3 cM) and another segment on chromosome 3 that is 7.2 cM that only my brother and I share with her – my dad doesn’t share that segment so I know we must also match through my mom!
good inference! although of course it could possibly be a false match at that size. See http://blog.kittycooper.com/2014/10/when-is-a-dna-segment-match-a-real-match-ibd-or-ibs-or-ibc/
i share546 centimorgans shared across 24 DNA segments with a match …
trying to figure out the relationship ..she said its her moms side of the family and she is the half sister and her brother gave a baby girl up for adoption ??
Deanna – I am not sure what you are asking. That is on the low side, but the DNA match could be a half-niece relationship. If you are an adoptee or she is, then I recommend the DNAadoption.com web site plus join their mailing list at yahoo and ask questions there. Or DNA detectives on facebook.
My Mom shares 89.8, 3 segments (chr 1,18,21) longest 74.4 (chr 1) with a male match and
she also shares 187.2, 6 segments (chr 5,6,7,9,14), longest 78.4 (chr 9) and (chr 14 at 41.5 and 15.3) plus 26 “X” cMs with another male match. Any significance in 2 long segments within one chr?
I’ve found the same MRCA in their trees but they don’t match each other on Ancestry or Gedmatch! It’s like they’re not related to each other (and not in common with my Mom) but I know they share this Hood line. Can you share any wisdom on this issue and both having long segment matches with Mom? Both are in their 60’s and Mom is in her 80’s…
Mom’s 187 match thinks it’s possible his great Uncle or a 1/2 great Uncle may be my Mom’s great grandfather. Which means they would share a 2nd great grandparent. I’m having trouble with this because they share more DNA than 3rd cousin level? Thank you!
My apologies, I seem to have missed your comment. How long ago do they share the Hood line. A few 3rd cousins do not match at all (10%) and about half of 4th cousins do not match. See
And that is a fine amount for 3rd cousins to share. Blaine’s latest chart shows average 79cM and range 0 – 189
The amount of DNA shared past 2nd cousins gets more and more random …
Hi Kitty, I am trying to find my Ashkenazi father. This is one of my closest matches from his side from Gedmatch. Any insight on what type of relationship this is with the endogamous component. Trying to decide if it is worth proceeding with, what do you think? Thank you so much for considering.
Minimum threshold size to be included in total = 500 SNPs
Mismatch-bunching Limit = 250 SNPs
Minimum segment cM to be included in total = 7.0 cM
Chr Start Location End Location Centimorgans (cM) SNPs
1 242,426,244 245,689,563 8.9 634
3 5,828,299 71,791,127 78.9 10,022
6 6,813,583 10,288,551 7.1 588
16 60,358,369 76,240,659 12.9 1,896
Largest segment = 78.9 cM
Total of segments > 7 cM = 107.8 cM
4 matching segments
Estimated number of generations to MRCA = 3.5
397067 SNPs used for this comparison.
Definitely worth pursing that match, about a 3rd cousin, 2C1R, 3C1R, 4th …. the large segment is promising for a closer match.
See Lara Diamond’s family statistics for an idea of what endogamy does to shared cMs in relationships past 2nd cousins:
My new rule of thumb for DNA cousins past 2nd on the AJ side which meet the one segment > 20 and another > 10 criteria is to halve the total cMs and then look that number up on the chart …
Largest segment = 52.2 cM what does this mean ? a 3rd cousin match ? thanks wendy
Sorry Wendy, I seem to have missed your comment. a large segment like that is usually closer family 3rd cousin or closer but it is the total cM which we use to estimate the relationship as in the chart shown above.
Hi, i cannot find the segment lengths from my testing company. I surprisingly matched to several members of a family I do not know. They range from less than 400 cM to around 175cM, over 12 but under 20 segments. Is there any way that this possibly is IBS? I did this for med info and ethnicity for fun, this matching was a total shock. Please advise.
BTW, Do you do consults? Kind of…..bowled over.
These are in the range of 2nd cousins or so. See http://www.isogg.org/wiki/Autosomal_DNA_statistics
Have you contacted them yet?
Thank you for your article. It has been one of the most helpful in trying to understand smaller segments and their possible significance or non-significance.
I understand that if there are a small number of matching segments, there is little chance of relationship.
If there is a segment that is over 7 cMs and it is accompanied by a small number of matching segments, it may or may not support the indication of relationship.
My question is, because I have a number of matches where this is true, I will have a match with someone where the total of matching segments (using the 7 cM default) is over 25 cMs, even up to 60, and those matches are accompanied by a large number of segments (20 to 30) which are smaller giving a total number of shared cMs between 60 and 100.
Do those smaller segments support the relationship?
Do they indicate a closer relationship?
Does paying attention to the chromosome where the segments are found help to understand? (For example, on the 8th chromosome there are 5 segments which add up to 12 cMs)?
Thank you for taking the time to answer.
My advice is to ignore most of the smaller segments below 7cM and use the total of the larger segments with the chart to make a guesstimate of the relationship.
Sometimes the 6s and even the 5s can be valid and triangulate with other relatives but for the most part they are false.
Having many of the smaller segments will often occur when you are from the same population group so likely you have shared ancestors many hundreds of years ago, further back than the records. That is all a plethora of small segments might indicate. Not relevant to the closeness of your relationship.
I have tested with several DNA companies & my closest match on my Ashkenazi side is on MyHeritage. The match is:Shared DNA 1.7% (125.2 cM)
Shared segments 4
Largest segment 82.8 cM Is This a match worth contacting etc. I am an adoptee searching for my birthfather.
Yes that is a match worth pursuing. I have lots of blog posts on Ashkenazi DNA, try this one
I am reposting an issue of mine, to get an expert opinion (analysis) from someone on this Blog who maybe an expert on small segments. I’ve read there is a lot of debate on the topic and is usually negative. I’ve read ISOGG and Blaine Bettinger’s blog and others. There is an issue, where on a surname line came from the same small town as my same surname line came from. I really thought we were related as 4th to 5th cousins. Ancestry match results bottom’s out at 6 cM. With the background on my line, some of the matches with my surname, I would say the cM’s shared were really low in that my grandfather and my great-great grandfather did not pass much shared DNA down to me according to a chart, ‘DNA Detectives Autosomal Statistics Chart’ and other online statistics charts. I was wondering to myself, how would I match to 4th to 5th cousins, or have the same common 4x great grandparents.
So I uploaded the results to GedMatch which you can lower the Centimorgans to 3. I compared myself to the other line with start to end as follows: 23,278,836 to 28,530,339, 4.5 cM, 900 SNPs on Chr.5 and 27,093,528 to 47,702,256, 5.0 cM, 1,220 SNPs on Chr. 16. I compared myself to the other line’s Aunt with start to end: 23,568,400 to 28,355,305, 4.2 cM, 823 SNPs on Chr. 5 and 27,273,899 to 47,576,695, 4.4 cM, 1,126 SNP’s on Chr.16.
I checked my niece’s kit to the other line realizing that she would be a generation offset(more distant) and this dropped the Chr. 5 results. I compared her to the other line with start to end as follows: 27,729,894 to 47,573,693, 3.5 cM, 1,021 SNP’s. I compared her to the other line’s Aunt with start to end as follows: 27,729,894 to 47,573,693, 3.5 cM, 1,015 SNP’s on Chr.16
All three of us have common, somewhat overlapping segments on Chr. 5 and 16 with somewhat strong SNP’s, with at least 4 cM not 3cM’s. Even my niece’s less than 4 cM’s results, hung in there with Chr.16 with rather large SNP’s. In some study on small segments that quote, “When utilizing small segments, I generally don’t drop the SNP threshold below 500”. SNPs are larger than 500.
My ancestor did change his first name when he came to America on the boat, but there are documents such as parish/church records from here and in Germany. Why he changed his name, not sure why, but it could be a confirmation name which are not documented in parish records in Germany.
Would you think that my line and the other line with the same surname are related (Identical by Descent)?
This is way too complicated for a quick answer on my blog but yes this could be valid, especially with a large number of SNPs. Test more cousins on each line to try to confirm. Oldest generations best.
Small matches in cM of 4-6 with high SNPs are possibly valid if they triangulate but beware, these can also be population segments. Look at who else matches you there.
This seems high for a 2nd cousin. I know who it is, we thought we were 1/2 first cousins. Isn’t this more within a 1st cousin range? Thanks!
Chr Start Location End Location Centimorgans (cM) SNPs
1 59,215,941 120,075,978 59.4 6,288
1 179,426,082 194,391,631 11.9 1,085
2 42,188,689 74,825,589 33.0 3,734
2 77,198,999 119,936,267 27.8 2,853
3 38,411 28,993,092 51.8 4,120
3 128,952,856 157,910,521 30.3 2,676
3 185,884,816 196,259,734 26.1 1,422
8 30,337,787 68,738,971 25.8 2,556
9 5,686,021 33,398,019 43.0 4,039
9 71,030,216 79,391,121 9.2 1,007
11 10,373,830 107,128,834 91.8 9,180
13 35,350,141 111,813,664 92.5 8,150
15 67,889,745 98,108,585 52.3 3,753
20 24,474,724 53,492,826 33.5 2,768
22 14,884,399 24,620,588 25.9 1,091
22 25,392,038 49,524,956 50.4 3,300
Largest segment = 92.5 cM
Total of segments > 7 cM = 664.6 cM
16 matching segments
Estimated number of generations to MRCA = 2.2
That looks fine for half first cousins, a little on the high side but DNA is pretty variable. It could also be full first cousins as you suggest. Another possibility is that the parents who are not expected to be the same are related. Any endogamy in that tree?
You can confirm the full versus half by testing 2nd or 3rd cousins or other close relatives that you expect NOT to be related to both of you. If they are only related to the expected person, that would confirm the halfness. If they are related to both, but very unequally, it could be the related issue. So you may need to test even more people.
My Mum has a match from another country with an SNP of 627 and 8.6 cM. It states around 6.8 Generations. Is this a positive match? This match would mean us. Thank you:)
That size is more likely to be a good match than a false one.
But there no way to estimate the exact relationship, since single segment matches can be from ver far back, anywhere from 4th to 14th cousins, see http://ongenetics.blogspot.com/2011/02/genetic-genealogy-and-single-segment.html?m=1
Here is an article that details the probability of smaller matches like this being a true aka IBD match
Thank you so much. 🙂
GED states that a good match has to be at least 700 SNP and 7 cM. Would that be true even if the numbers were close?
GEDmatch is basing that guideline on the article I gave you the link to. Your match is about 50% to be a good one but is likely to be pretty far back in time.
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Awesome. Thanks so much. Its pretty exciting to me. My ancestors were traded, so having a match from the continent is very amazing. I understand it will be very distant though. I will be testing much older relatives to see if they have the same match too.
Four of us sharing a very rare Irish surname amongst known ancestors have been lucky enough to separately stumble upon each other during Internet searches during the past several years. From family histories and records, we all knew we had rare surname ancestors coming from the same small area in County Mayo, Ireland dating to early through mid-1800’s. Based solely on family histories, we wondered if all four of us might have the same great-great-great grandparents or great-great-great uncles/aunts. This month, we all posted our DNA test results at GEDmatch to see how or if we match. The results are a mixed bag. For one person (I’ll call “Judy”) for whom I suspected (before DNA testing and from family history) her known great-great-grandparents might also be my “lost” great-great-grandparents, the GEDmatch 3D Browser showed that she and I matched on 14 different chromosomes and a total of 27 segments, for a total shared cM of 77.5. However, all 27 segment values are on the low side, with the highest being 5.2 cM. The others were: 3 segments between 4.0 and 4.9, 17 segments between 3.0 and 3.9, and the rest less than 3.0. So, lots of Crs, segments, and total cM but very modest segment values. For this same “Judy” person, another one of the four of us showed a match at or above 3.0 on only 8 different chromosomes and 9 segments, totaling to 35.0 cM but with the highest segment at 9.1. So, a higher highest value than mine….but on much fewer Cr’s and segments. Does the fact that I match on many more Cr’s and segments, but with a lower highest value on a single segment (5.2 cM vs. 9.1 cM) imply any greater probability of a 5 or 6 generation common ancestry to “Judy”?
Matches below 7cM are often false which is why we look at the total of segments > 7cM. Your matches are too small to be conclusive.
For a rare surname the best strategy is to test the Y of the men with that surname, at least 37 markers. At family tree DNA (use my link in the footer so I get a little credit). This reaches back many hundreds of years, much further than autosomal which is not guaranteed to produce matches beyond 3rd cousins ….
Also please note that those 37 marker Y DNA tests are on sale until father’s day!
My affiliate link:
I have a niece who tested at both Ancestry.com and MyHeritage. The results came back 880 centimorgans and 50 segments on Ancestery.com but 403 centimorgans and eleven segments on MyHeritage. What will be her predicted relation to me(uncle). Thanks in advance for your reply
The ancestry result suggests she is a half niece, that is to say her parent that is your sibling is likely a half sibling.
Does she match relatives on just your maternal or paternal side? Test a few cousins …
So did either of you actually test at MyHeritage or did you upload your results from ancestry? The same company and chip? I would contact customer support at MyHeritage as that seems too large a difference.
mskitty I uploaded my data from ancesterydna to MyHeritage, my niece match relatives on my maternal side of the family. I am assuming her father and I are half sibling. My brother is having a hard time with this since I am name after our father. Who is decease. Thank you for your reply!
These situations are always hard and often a shock. You might both read the story of how DNA affected a genealogist and newsman when he learned his Dad was not his biological father – The Stranger in My Genes by Bill Griffeth.
To confirm, perhaps your brother would DNA test once he is ready. I have an article on how to tell if you are half siblings – http://blog.kittycooper.com/2016/04/full-versus-half-sibling-dna-matches/
Thanks Kitty, your comments and reply has been quite helpful! I will read – The Stranger in My Genes by Bill Griffeth.
Our family is trying to solve a brick wall. I am using the Blaine T. Bettinger chart which was updated March 20, 2017, and goes out to 8C.
Cindi (my 1C1R) and I have both tested with Ancestry. We both match Tina, me at 56.7 cM over 1 DNA segment, and Cindi at 37.8 cM over 1 DNA segment. Using the Bettinger chart, I figure that Tina is my 4C1R, because it seems that we share too much DNA for it to be a relationship which is further away. Notably, my sister Kim has 0 DNA in common with Tina.
It seems to me that 56.7 cM is a fairly large chunk of DNA, but I don’t understand the implications of it being over 1 segment, as opposed to, for example, 3.
I welcome your insights and suggestions
Those are large matches but they are just one segment. The problem with one segment matches is that it can be from quite far back and just happened to keep getting passed along. See
After 3rd cousins the amount of DNA shared cannot be accurately determined. The chart is just a set of estimates. Because your matching chunks are so large, a 4th/5th cousin is probable, but by no means for sure.
Hi Kitty! I hope you can answer this for me! I was adopted and recently did a DNA test on Ancestry, many surprises in my ethnic background, however I am more curious about a match who came up as a first cousin, I am thinking she may be my half-niece. We share 947 centimorgans over 45 DNA segments. Her sister, who has a different father than her had a lower match 639 centimorgans over 32 DNA segments. Is this at all possible? I ask about the niece match because her uncle and I have spoken often and his father matches almost exact what I was told about my bio dad and the ethnicity matches as well. Thanks in advance for your help!
Sorry, if you match both sisters then you are related to their shared parent, the mother. Both matches are within the range for a half-niece or a full first cousin. Are they sure they are half sisters?
Yes, they have the same mom, but different fathers. This is all so strange and confusing for me! Thanks for your reply!
I’m just starting with all this, and it’s like learning a whole new language! I’m sorry if my questions seem rather simple. I tested with 23andMe, uploaded to all the usual spots. I’ve got my Ancestry test pending. Trying to find biological family.
So, when I look at these comparisons, what is the most important thing to be looking for, length of segments or number of segments? I have one who we share 36 cM on one, with 2 other, smaller segments. Also, I’ve found 2 other people who share almost the identical segments with me and the first person. Would that indicate that the 4 of us share a common ancestor?
Also, I have another person who shares 46.6cM on a different chromosome, but only that one segment.
Are any of these significant? Thanks for any help you can give.
Yes it is a whole new language. Please have a look at the methodology at DNAadoption.com then join their mailing list and join DNA detectives on Facebook. Lurk and learn. Maybe take a class at DNAadition.
With 4 million testers, Ancestry seems to have reached a tipping point where most adoption cases with American roots can be solved. See the GWorks and mirror tree methods described here:
I just solved another case this way, 4 days after her Ancestry results were in (but it was an unknown dad only). I plan to make an adoption summary page here soon.
Back to your specific question, did you check if the four of you all match each other? Remember that there are two chromosomes at every position, see
Also Brenda, none of those matches sounded large enough to be closely related. Total cM > 7 is a good indicator, see
But if they have trees, collect them, they may be useful as you get more matches.
Great article! I have a known second cousin who tested at FTDNA. We did not match, but he matched my grandmother who is his dad’s first cousin. When I uploaded our results to gedmatch, we only matched on one segment at 13cms (he matched my grandmother at about 300cms). The predicted relationship was 5th -8th cousins! I really expected us to have a higher amount of shared DNA because everyone else in my family who tested matched him pretty high. If I didn’t know our MRCA, I would have discounted it as being really distant.
Your information is quite helpful to me, but I am having a problem identifying cm numbers which are relevant for me. My mother was adopted and I am searching for her family. I have tested on both Ancestry and FTDNA and find the cm matching counts to be so different. I have quite a few matches who have also tested on both and the results can vary significantly. They difference can range from 10 cm on Ancestry to 60 cm on FTDNA and other similar differences. When there are not many very high matches for me to pursue, I would like to know which testing company’s results are the most helpful for my purposes. Thanks for your help.
Ancestry removes matching segments which are population specific or pile ups. this is very helpful for those from endogamous populations like Ashkenazi Jews but does result in a smaller total. family tree DNA includes many small segments which can sometimes be useful, but results in a higher total.
GEDMatch one to one gives the total of matching agents > 7 cM so that is the best number to use
Also Judy, DNAAdoption has a good chart that includes numbers for ancestry here http://dnaadoption.com/index.php?page=dna-prediction-chart-pdf-2
Here is the white paper explaining the segment matches ancestry removes https://www.ancestry.com/corporate/sites/default/files/AncestryDNA-Matching-White-Paper.pdf
Hello Kitty, I have had a DNA test done by Ancestry.com. I am very puzzled by one particular relationship result. I share 1485 cms across 50 dna segments with my father’s first cousin, my brother is 1146 cms across 45 dna segments, suggesting (to me) that this is an aunt, not a cousin. My four children range from 747-915 cms across from 28-36 dna segments, suggesting a first cousin. My logic (hopefully wrong) is that my grandparents were siblings. I’m not completely shocked, but saddened as this would go far to explain a family split in the 1930’s. May I ask your opinion? Thank you, Broertje
These are both within the range for a first cousin to you two but too high for a first cousin once removed which is what your father’s cousin would be. Could this cousin’s parent be your father’s sibling? A within family adoption? Are any of your father’s generation alive and willing to test?
Only more testing can resolve this. You might also layout a McGuire diagram. If other cousins are tested, are they getting similar results? No I would not leap to your conclusion yet
Kitty, thank you for your very helpful reply. This cousin of my dad’s has a brother and sister still living, but I’m not sure if I can convince them to do a test…..I might have more luck with her son. I haven’t even considered telling them that their much loved father might have done the unthinkable, even if I was absolutely certain. There are no others left of that generation. I don’t believe she was dad’s sister, she’s the middle child of my great uncle and his wife, and he and my grandmother and their sister were no longer on speaking terms by then. Sorry about all the details, but I am trying to be very thorough. I did suspect this a while ago and the DNA results are beginning to look like confirmation. I appreciate your help, it’s a relief to be able to ask an expert questions.
Correction…..the numbers don’t stack up for dad’s uncle to be his sibling
My mum shares 342 cM over 13 segments with a man only on Ancestry who won’t share their tree – help ! * and with a great grandfather to find we think it is THAT crucial line. What to do ?! Could his great grandfather or great uncle, or grandfather or uncle be my mums grandfather ?
Correction – I meant ” * and with a grandfather (of my mother’s) to discover we think it IS THAT crucial line. What to do ?! Could his great grandfather or great uncle, OR grandfather or uncle be my mum’s grandfather ? All advice very welcomed. The 3 shared matches don’t match each other and are very small cM.
Julie- this 1st/2nd cousin match could be any of those. Is he in touch with you? If not, try googling his username, sometimes that turns up an email address … also see
Have you tried using the GWorks technique to find that great-grandad? It works very well for those with American roots http://blog.kittycooper.com/2017/06/my-adoption-workshop-and-a-success-with-gworks/
I thought I found my (half) brother’s grandchild. The results show there are only about 545 cm shared between them. I share 632 cm with this child. Is this possible or should I be looking a generation back for answers.
If you share more DNA with this person than your half brother then it is almost surely not his grandchild. Any DNA his grandchild has in common with you would be from your half brother unless you are from an endogamous (very intermarried) population. Another possibility would be if that person is somewhat related to your other parent.
That amount of DNA could certainly be a half great-nephew for the both of you or a first cousin once removed
Have a look at Blaine’s latest set of charts for the possibilities
Hi Ms kitty, Thanks so much for having this blog.
I am very new to the world of DNA and adopted with no information on my biological family but I am reading as much as I can. DNAadoption has a lot of good information.
I did my DNA with FTDNA first then Ancestry. I did upload my data on Gedmatch. On FTDNA my first match I share 104 cM, total cM is 85.78. We have plenty In Common With also.
Are the numbers I share with my first match a good start or are the numbers on the lower side if I wanted to research the matches we have in common? Hope that all makes sense.
I really recommend you join the DNAadoption mailing list at Yahoo and/or DNA Detectives at Facebook and ask questions there. Better yet take a class at DNA adoption
That match is a start but not the 2nd cousin match or better you would hope for, since 106 is only about a 3rd cousin or 2nd once removed. Still with enough of those matches, you can find your biological family but it won’t happen overnight.
I completed an AncestryDNA test. I shows I have a close relative. We share 1,656 centimorgans across 64 segments. What is your take on what their relation may be to me?
Hi. My wife also completed an AncestryDNA test. It shows she shares 1,788 centimorgans across 78 segments with a woman. She contacted the woman and it turns out the woman is adopted with a half-sister. This woman and her half-sister share 1723 centimorgans across 76 segments. Does this mean my wife is most likely a half-sister to this woman?
AJ and Gil –
These matches fall in the half sibling range. The other possibilities are grandparent (usually ruled out by ages) and aunt/uncle or niece/nephew. If you can compare them at GEDmatch you can perhaps tell them apart.
Ancestry removes DNA areas that are less significant so tends to show more segments and fewer cMs than a straight one to one comparison at GEDmatch
I have several posts on this subject, the most recent is the collected statistics here:
Thanks Kitty! We are doing GEDMatch right now and may have some follow-up questions. Good night.
Could a 545 CM match be a half 1st cousin?
Yes it could be. Check Blaine’s latest chart for the ranges of relationships
Hi. I took the Ancestry DNA test and a woman showed up as a 1st-2nd Cousin. Although she’s predicted to be a 2nd Cousin. It says we have 406 centimorgans shared across 25 DNA segments. I don’t know this woman and her alleged parents and grandparents or great-grandparents are not related to me. I’ve have researched my genealogy for over 15 years and her alleged family doesn’t appear anywhere on our tree. What are your thoughts?
The most likely relationship is 1st cousin once removed or half first cousin or second cousin. There are many possibilities along those lines.
As to how this could be, she might be adopted and that is her adopted family’s tree. She might not know she is adopted. Or you or she could have an unexpected paternity event (NPE) where one of your grandads or great grandads is not the name on the birth certificate. What is your age difference?
Start by using Michele’s tip number five to verify all your family lines
Then contact your new relative and work on this together.
Thank you! And thanks for replying. She and I are the exact same age and she curiously resembles my own mother (I saw a FB photo). Btw, she’s related on my mother’s side of the family. My mother’s FATHER side. I thought perhaps she was one of my mother’s brothers NPE children. Or perhaps even my grandfather’s NPE child. But now that you’ve mentioned once-removed I do wonder if she’s one of my mother’s first cousins’ NPE daughter. She also shows up as an exact 2nd Cousin for my nephew. They have 258 centimorgans shared across 15 DNA segments.
She could be any of those things, get some more family members to test whose results will help narrow this down … Cousins, uncles …
Is there anything like this for large X matches. I working on a match that share 138 cM on the X but only about 8 cM autosomal. Any ideas? There is one other match that has 58 cM of the same segment.
X matches are much more variable than autosomal matches because the X passes through males without recombination. So no they cannot be predicted.
Since a small autosomal match is included, my guess would be a 3rd cousin or 3rd once removed.
Kitty, I have a general question for you. My DNA show 100% European and I have some really good matches, many of whom I’ve been able to confirm. My husband has 66% Native American ancestry. I noticed that my closer matches are much lower total cM matches, but larger segments. His closer matches can be MUCH bigger in terms of overall cM, but the segments are usually quite small. Is that something to do with the gene pool? I’m Heinz 57 from many countries and his ancestry from both parents is from a small area in one country.
Likely his closer looking matches are not as close as the total cMs indicate. If they are all from one area, there could be cousin marriages affecting the amount of shared DNA. Also small segments can be population specific as opposed to recent common relatives.
Your close family out to about 3rd cousins will share larger chunks. Also do not use the totals from your testing company, best to total all the segments > 7cM yourselves. Anestry totals are OK but upload the data to GEDmatch to see the segment sizes.
I wouldn’t trust Ancestry. I used ftdna and then uploaded to gedmatch. I’ll used the >7cM rule on his and see what it looks like. I was pretty sure that the smaller area and possible cousin marriages would affect results, but I wanted an expert opinion. Thanks so much for your blog and for the very fast reply. Much appreciated!
The default at GEDmatch is > 7cM so that is easiest and best!
All other things being equal and assuming no endogamy, can you give us a generalization regarding the interpretation of a situation where you have 2 12 cM segments vs a single 24 cm segment? How would chromosome location factor in, e.g 2 locations on same chromosome vs 2 different chromosomes? I am concerned about probability vs “magic thinking”.
It is not possible to give much of a generalization because of the randomness of DNA inheritance. I would feel more confident that I could find the relationship to the person with the two segments but often that can be each from a different ancestor so still pretty far back
Glad to hear that. One of my ‘hooks’ to encourage AncestryDNA matches who share multiple segments to post their kit to gedmatch is the possibility of finding two sets of MRCAs for the price of 1 (especially when the shared matches showing in Ancestry are mixed between 2 diff lines – I code all matches based on their matches). But, as the number of shared segments > 7 cM increases, does that not undermine the assumption of independence, statistically speaking, because of proximity and the likelihood they came from the same line generally speaking?
(code matches based on their shared matches with my target kit, I meant, regarding coding matches)
It just depends on how small a population pool those ancestors had as to how likely it is that two segments = two MRCAs. I start with the assumption that it might really be a 4th cousin match or so with one MRCA.
Thank you for taking the time to talk about this while I struggle to ‘debug’ my thinking. Because I come from mostly early colonial era in the US except for one line that got here in 1840, I am very used to seeing my ancestors in random trees all over the place so it wouldn’t surprise me to have 2 sets of MRCAs for 2 segs, but I am struggling with “magic thinking” — always a problem when working with probablilties. I must imagine that the closer the match AOTBE the more likely the segments came from the same line in my tree but with different possible MRCAs in that line but that a couple of smaller segments for a match who shares less cm could have come from 2 different lines and MRCAs as they get further back in time where there are many more degrees of freedom. But, then I imagine that it’s not necessarily as independent in the statistical sense to the degree that the multiple sets of MRCAs are coming from the same area/ Does that make sense? Similarly for the case where the two segments are on the same chromosome.
DNA inheritance is too random past 2nd/3rd cousins to apply much math. Large segments are good and tend to be from more recent ancestors. Single segments are less likely to be findable than two large segments. However as we said, two can be from different lines so just as hard to find.
When your ancestors intermarried it gets more difficult to figure these out.
My advice is to start with your closer matches first – I love this slide I did to illustrate that http://slides.com/kittycooper/dna-test-results2#/27
Kitty, thank you so much for taking time to discuss this with me. Regarding starting with closer matches, I completely agree but on my mom’s kit I’ve solved as many as I knew personally and most who posted to gedmatch or had kits where a chromosome browser was at hand, but since I only had the kit for her, I’ve been testing this approach: made a master spreadsheet of all her matches using gedmatch Matching Segs: then decomposed them in to two groups for every discreet group (no overlap); then based on who was in the segment, classified them as maternal or paternal when I could based on trees or the fact that I could reliably identify the other segment with that address range. where there was no overlap I provisionally marked it as a potential recombination and/or crossover point until/unless an overlapping match turned up. Then I set about classifying segments based on the big cousins where I could. I tried Visual Phasing in the cases where segments were big enough. I used triangulation to test my assumptions.
I used logic to interpolate as many big cousins from 23andme and ftdna who had not posted to gedmatch. I also use a system coding ancestry matches based on who they match even where the line was unknown when necessary (e.g. “mystery cluster z”). My biggest takeaways from my approach were as follows (1) how often I would have been wrong relying on Ancestry without segment matching, (2) how interconnected those of us with deep US southern early colonial era ancestry are and (3) the hell of Scottish pedigress 🙂 ….BUT my biggest challenge has been the problem of “magic thinking” regarding probability SO THANK YOU FOR YOUR PATIENCE AND WISDOM!
Hello are you still posting or answering questions? Thanks
I am researching family for my fiancé,he was adopted. On Ancestry DNA I have found people who are showing up as second cousins to him. And there are numbers beside their names such as this :465 centimorgans shared across 21 DNA segments ,407 centimorgans shared across 20 DNA segments. What does that actually mean? Because in my case I had someone show up as a second cousin and she was actually my aunt my dad’s half-sister . So how am I to tell if these people who are coming up a second cousins ,predicted second cousins for him or actually second cousins and not a first cousin or something else ?Thank you
A 2nd cousin as you already know can be any one of a number of relationships. If any of his 2nd cousin matches have trees, you can try the mirror tree technique to figure out which line he shares with them – see how here http://www.borninneworleans.com/how-to/what-is-a-mirror-tree/
Another good thing to do is a GWorks run where you let the automation at DNAgedcom compare the trees of all your matches, usually just out to 4th cousins see http://blog.kittycooper.com/2017/09/solving-unknown-parentage-cases-with-dna/
This can be donw but it takes time and often online sleauthing as well. See http://blog.kittycooper.com/dna-basics/help-for-adoptees/
for more thoughts on your search
Hi, what in the world does this mean?
This is my first and biggest hit, he’s a white dude in Virginia, I was born in Mexico.
Shared DNA 12,9% (934 cM)
Shared segments 25
Largest segment 78,1 cM
That is a nice close match, perhaps a first cousin or half uncle, what are your relative ages? Where did you test? Did you think you knew all your bio relatives?
This calculator can be very useful
Forget about that white thing, we are all human and all mixed, mexicans often more so than many!
Kitty, Thanks for the great information. I have someone who matches my fiancé for one segment of around 27 centimorgans on chromosome 16 and a couple of other segments on two others. She has six segments of around 3.5-4 centimorgans on the X. Given she is a match on other chromosomes of over 7 would several smaller segments on the X indicate an X match?
Maybe if the someone is male, more likely these are false or population specific segments. X matches of less than 10 cM for a woman are always dubious because a woman has two X chromosomes to match to, so false matches are frequent. To understand false matching see http://blog.kittycooper.com/2014/10/when-is-a-dna-segment-match-a-real-match-ibd-or-ibs-or-ibc/
Thanks Kitty. I appreciate you answering the question. I assumed this was probably the case but wanted to check.
Hi Kitty – Thanks for this information. Question. I have at least 12 DNA matches to both me, my aunt and uncle and all of these matches are of the same surname. Because we are related to these matches 7-9 generations (according to Gedmatch) back I reduced my Gedmatch search to 3 cMs and 300 SNPs. Total segments in common vary among our 12 matches anywhere from 23 to 6. Total shared cMs range from 96.5 to 21 cMs. Would you say this was indicative of a shared ancestry?
I would not reduce it that far. I use 5cM and 400 SNPs when lowering thresholds for known family. But the segments are still likely to be false if the SNP count is low.
However from what you are saying this is a set of matches worth pursuing which may well include a common ancestor. Warning, if they are from a group that has intermarried alot, then this could be misleading.
I am adopted and I entered my DNA in ancestry.com. Eventually, by matching basic DNA data from ancestry with two relatives (who turned out to be a cousin and half-sibling) I was able to determine the identity of my birth mother. I was able to conclusively do this by using other information, such as ages, time periods, and non-identifying information from the adoption agency. Now I think I have found the family, generally, of my birth father, But I don’t have any of the additional historical information to augment my search, One relative on my father’s side registers 1,767 cM across 50 DNA segments, Another registers 999 cM across 40 DNA segments. I haven’t yet been able to convince either to go through GedMatch. I’m assuming the first is a half-sibling and the second is a first cousin. Is there any way besides comparing downloaded data to make a conclusive determination? One thing that confuses me is that in the case of two half-siblings on my mother’s side we shared 60 DNA segments exactly, but in the case of the one relative on my father’s side who registered 1,767 cM we share only 50 DNA segments. Shouldn’t half-siblings, whether they come from one side or the other, share the same number of DNA segments with me?
Actually there is less recombination done on DNA inherited from a Dad, so they are usually different and less segments is normal.
Try convincing them to upload to family tree DNA if they are concerned about GEDmatch, there is more privacy there. Only people who match you can see your results.
Hi. I’m following a line that comes from the Azores so endogamy is confusing me. The lines starts a while ago so any DNA match to do with that line will be 3rd or 4th cousins. Would a match that shares 50Cm on one segment be better to follow than a match that shares a total of 50Cm across 4 segments?
More large segments is best.
Single segment matches can be very far back in time, even large ones like that one. I would prefer a match with 50cM on 2 or 3 segments but 4 is good too.
An old post but very good.
If I understand correctly, even a large single segment of 50 centimorgans can be a very distant cousin? I have many matches on a single segment from 30-40 centimorgans. Using the formula for probability of recombination (i.e, (1-e^-2d/100)/2), I found that even a 40 centimorgan single segment has a 10% chance of staying intact after 7 generations.
Therefore, am I right in assuming that single segments are more distant than matches with multiple > 7 cm segments, regardless of size?
Thank you for all of the great geneaology resources!
~ Katherine ☺
40cM is an awfully large segment to have stayed intact for so long but if you have many matches there it could be a pileup or a case where that bit of DNA inverted so it cannot recombine. In either of those cases it could be quite old.
It is not that single segment matches are always more distant than those with the same total in smaller segments but that they are quite likely more distant.
Multiple segments > 10 cM are the best for being able to find the relationship. I have seen cases of 2 or 3 segments in the 7-8 cM range which seem to be from multiple far back ancestors (1500s, 1600s).
Thank you for your response! I should have clarified that the *majority* of people in these triangulation groups match me at 15-29 centimorgans, while 30-40 centimorgan segments are the maximum length, only matched with 1 or 2 people in that group (usually a parent and child).
My mom was adopted many of the people one of the triangulating segments (including the one with 40 centimorgans) appear to have a common ancestor from the 1700s.
By a pileup region, do you mean a segment that is identical by population? Also, thank you for bringing up the idea of inverted DNA; I never thought about that.
On my GEDMatch I have 2 matches where I am curious and have a question regarding.
One is a match that shares 214 cM total with the longest being over 39cM… what level of relation would that hypothetically be?
The other only shares a total of 53.7 cM however I only have one segment of 53.7 cM in length that I share with them. Is there a reason that we would share a segment so large, but it only be one segment? Would that be a relation worth looking into?
Thanks in advance for the info,
Pile ups can be real but too far back to find. See this blog post
You can look up the 214 here:
As to the single 53 cM segment, up to you, could be close or far. The calculator above is not helpful for single segment matches. Read this article, old but good:
I would not spend alot of time on it if it is part of this pile up
There is a calculator which you can use to figure relationships out at: https://dnapainter.com/tools/sharedcmv4
The 214 is likely about a 2nd cousin.
The single large segment can be anything from a 4th to an 8th cousin. Segments can last for a surprisingly long time and the further away the relationship the wider the range of shared DNA. I find that single segment matches are often too far back to find so look at other matches first.
Hi my brother did an ancestry DNA test and was matched 1557cm across 57 segments to someone . I don’t fully understand this and now my whole family is in turmoil as he is insistant that the person who is matched with us /him is our older half sibling. This person has found their birth mother who actually named my father’s uncle as the person’s father.
Please could you explain what all this means and would my brother be matched this way if the person NOT my fathers child?
DNA does not lie. With that amount shared this match likely really is your half sibling.
One other possibility is that this person’s mother is also a relative of yours so the match shares DNA from both sides. In that case the uncle could be the father. But DNA is more reliable than a birth mother’s statement.
The other possibilities do not match your description of his age. Use this calculator and plug in the numbers https://dnapainter.com/tools/sharedcmv4
Tell your brother he can send me more information via my contact form (like GEDmatch kit numbers) if he wants more proof/evidence.
Take a deep breath and welcome your new relative into your lives.
Thank you Kitty I think you are right ….
I had my DNA done. One of my dads sisters; my (aunt) came up as my cousin. How is this possible the cm 1015 the segment was 37. I asked her about she said no honey I am your aunt. The number don’t line up.
I just had my DNA tested and I matched one person with 403 centimorgans across 23 segments of DNA, what does that translate to?
Most likely a first cousin once removed or a half first cousin but there are other relationships that could share that much DNA. Input the numbers to this calculator to see all the possibilities
I match someone at 64 cMs on one segment and we can’t find anyone in common on our trees. Do you think this could be a link to an unknown 2nd G Grandfather?
How many segments? Which company?
This is usually in the 3rd-4th cousin range but can often be two further back ancestors or … many variations. Once you are past 2nd cousins DNA gets more and more amorphous and varied in how much you share …
I found a predicted cousin that share 556cM and 23 segments, what are the other relationship possibilities here?? Trying to locate my bio mother
There are a number of possibilities, use the calculator
Perhaps the most likely is a grandchild of a sibling of your mother (1at cousin once removed) but there are others. What is the age difference between you? Have you been in touch?
DNAadoption.com has much help, they advise making a copy of the person’s tree before contact and not mentioning adoption right away.
I’m a frequent visitor, but its my first time posting.I had a question regarding segments. I had my mother take a DNA test early last year on Ancestry (later uploaded to FTDNA and GedMatch) in hopes that I could find more about her maternal grandfather who was unknown to us.
I have isolated several extremely high matches of 100-298 CM’s tracing back to a particular couple with a name and location that does not match any of her relatives for her father or her known maternal lines. This makes me think that the DNA is from the unknown line.
This couple in question had 3 sons, and she shares almost 300 CM with descendants of 2 of them. I realize that 300 CM could ether be a half 1st cousin 1x removed or a 2nd cousin, but I’m wondering if the shared Segments could offer a clue as to which is the closer relative? One she shares 298 over 10 Segments, the other 295 over 14. Is there any way to know? I am hoping someone with a better understanding of the subject can help. I thank you very much for your time.
Exciting, if the dates work then that couple could be her great grandparents. Yes those would seem to be second cousin matches. Or possibly the husband is unknown grandad (half1C1/2R)? Are there matches further up the tree for both members of the couple?
What generation are those large matches? If the same generation as your mother then the most likely possibility is that the brother without tested descendants is the father. (2nd cousins)
Have you tried drawing a McGuire diagram? That tool often clarifies relationships
I recommend getting in touch with these cousins and explaining your search and getting more members of that family tested.
Also if you are tested at ancestry, if you all upload to GEDMatch then look at the X matches for these relatives if any are descended from daughters of those sons.
First of all, I can only imagine how dedicated you must be to this research to take the time to respond to each post. I am beyond grateful to have found you!! I am an adoptee with no biological information of either parent. I do have a surname and a city of birth but beyond that nothing. I have tested on ancestry and 23andme and have loaded results to gedmatch. The highest connection I have established shares 187 cm over 12 segments…3rd cousin possibly ?? ( I have several matches with similar amounts of shared DNA) woyld you please direct me toward any ecplprations that might be helpful in my pursuit of self discovery. Prior to DNA testing, I had no knowledge of my heritage. I am biracial. This journey is very important to me (and emotional for me) I have children who are just as curious about who they are biologically as I am about myself. What is your suggestion for someone like myself who has no foundation to build from? Is there hope?
Anything you can offer would be appreciated beyond measure. Again, thank you.
More likely a half 2nd cousin or a second cousin (possible once removed). You can figure it our from several matches like that, see
The technique I use is desceibed here
The calculator to use is
I recently did a DNA test and was matched with someone I do not know. It says she is a 1st cousin to me. We share 1,262 centimorgans across 40 DNA segments. That’s pretty high. I contacted her and she was adopted, so she doesn’t know who her father is. She has her mother’s name, but it’s pretty generic and I can’t find her. I have ruled out my maternal side because she has no Italian heritage and they are largely Italian. It must be my father’s side. Given her age, I am thinking my grandfather or great-grandfather would be her father. Do the centimorgans support that theory and I am way off base in thinking that?
Yes they support your theory. Likely your great-grandad – using this calculator it is 69% that you are her great niece and only 31% that you are her niece
See who among your relatives share DNA with her. If she shares DNA with 3rd cousins related to your great-grandmother then your great grandad is not her dad so your grandad
I share 517cm over 26 segments. This person is 81 years old and I am 48 years old. Would 1st cousin once removed be the most accurate relationship? I have looked at the charts and I don’t think Great-Great Uncle or any of the possibilities match up.
Yes 1C1R is the most likely if the other possibilities at
do not work with your trees
I have a specific question. I have a match that has one 70 CM segment and a second smaller one. So far we cannot find the MRCA through trees, though we know which side the match is on, and which town our families immigrated from (the town is the same).
So, what does is mean that the segment is so large?
A large segment usually means a closer family match but even very large segments can last a surprisingly long time. DNA recombination is very random so this match can be anything from a 4th to an 8th cousin. Or related more than once. Do other of your family members have this match?
I always thought my great grandmother was Ashkenazi Jewish and when my daughter took the DNA test, it showed that she was Ashkenzi Jewish. However, when I took the DNA test, there was 0% Ashkenazi Jewish in me. Is this possible for it to skip me, and for her to have the Jewish DNA?
No it is not possible for it to skip you BUT none of the companies are completely accurate yet as these predictions are an emerging science. Jewish is usually pretty clear in the DNA however, so probably that is from her father.
I would upload both your results to a few other sites and see what they say. Here is my article comparing various places:
I read your post to Reg about small segment sizes and wonder if a small segment size under 7 can ever be helpful in determining relationship. I have been in contact with 38 individuals who can trace their family name back to a small place in Northern Ireland within a similar time frame. We are trying to determine if there is a relationship between these individuals.
Some match others in the group for over 10 cM and some we know are related as 1st, 2nd, 3rd & 5th cousin but many of them match each other for less than 5 cM. How can I use the DNA match from those known cousins to help sort out if the others unknown individuals are a possible cousin. How much DNA would you expect a 5th cousin to possibly share.
Sorry, small segments of less than 7cM are usually false and worse you will only share DNA with about 10% of your 5th cousins (usually about 25 cM and often only one segment)
However if some of those small segments triangulate (are shared in the same spot by at least 3 people) you might go down to 6 or 5.5 cM … but that small is very unreliable, often false.
Read this though for an idea of what you can do
Pingback: Connecting the pieces of the DNA puzzle: How we found the donor. – Gin & Zin
Hoping you can help.
Oral history has it that my Great Grandfather was born in 1870 allegedly as a result of ‘kissing cousins’. I know who my GG Grandmother is and all that side of the family. I have now discovered a link between my line and another GEdcom user’s line. Without overthinking it would be natural to work back to the MCRA who would be the 4 x Great Grandfather. i.e. my GG Grandmother’s Grandfather who had 2 sons, one who had my GG Grandmother and another son who was the father of this particularly interesting chap, thus making them first cousins. The readings between this GEDcom user and my own are as follows:
Largest segment = 22.4 cM
Total of segments > 7 cM = 46.7 cM
3 matching segments
Estimated number of generations to MRCA = 4.1
There is no X match.
I should also mention this person has also uploaded her mother’s DNA test results on Ancestry (but not Gedcom) and these show the relationship to me as sharing 108cms shared over 5 DNA segments. Her mum is likely to be my generation.
Would I be right in thinking it’s entirely possible the chap who is her Great Great Grandfather is likely to also be my ‘Great Great Grandfather’?
I would have thought if our MCRA was the 4 x Great Grandfather then the DNA readings would be much weaker. That said, I am only just beginning to get my head around all of this and it’s quite fascinating.
I very much look forward to some guidance in this.
Have a great day:)
That match is in the 3rd-4th cousin range with there being multiple segments but as you say if your great-grandad’s parents were first cousins then this could be a match to that line. In other words, yes this is consistent with a double 4th cousin (both descended from your ggg-grandparents twice)
However, after 2nd and 3rd cousins, the DNA gets pretty random. The best approach is to test as many people descended from your g-grandad as possible, preferably the oldest ones. And same for your new cousin
Many thanks for your response. It certainly helps clarify what I was thinking. I think I’ll get my Dad’s DNA as he is one generation closer and the person I was referring to would be his Great Grandpa.
Thanks you once again.
I’ve just come across your blog and am hoping you can help me to better understand my Ancestry DNA results.
I’m adopted and I do know the match in question is from my fathers side and not my mother.
The match states 1603 centimorgans across 77 segments. I am female, this match is with a male.
I also matched with a female who I’ve confirmed to be his niece. My match with her says 648 centimorgans across 39 segments.
What I’m unsure of is whether this man is my half-uncle or half-brother.
I do not have access to his dna to compare on any other platform so I feel a little lost.
Am I correct in believing that this is a half-brother or is his brother my father?
Thank you so very much.
Please read this article but …
… you really cannot tell whether he is a half sibling or an uncle/nephew (if he is your father’s brother he is a full uncle) from the data given by Ancestry. The number of segments is high but the ancestry algorithm sometimes makes 2 segments out of one.
You would need to compare somewhere else where you have a chromosome browser, preferably GEDmatch, MyHeritage, or family tree DNA. Then look at the charts in that article. If he is a paternal half sibling you will typically share several segments > 100 cM while an uncle might share just one or none that large.
I have a third cousin once removed with whom I share 20.7 centimorgans across 1 DNA segment according my Ancestry DNA test. My daughter shares 29.9 centimorgans across 1 DNA segment with this same cousin according to Ancestry and my brother shares 46. My daughter’s father is not related to me. How is it possible that my daughter shares more centimorgans with this cousin than I do?
Boundaries of matches are not always accurate and a small segment that may be attached to her match might not even be a true match. For more about false matching see:
I would encourage all three of you to upload to Gedmatch and/or family tree DNA to look at the details of these matches in a chromosome browser.
I am trying to understand my DNA on Gedmatch as compared to a relative that I believe is my half sister or niece.
I was confused by one-to-one comparison that stated:
Largest Segment= 180.4 cm
Total Segments 7 cm = 1695.9 cm
30 Matching Segments
Estimated number of generations MRCA = 1.5
This information caused me to believe that the woman I am compared to is my niece, but then I did the X-one-to-one and the results were:
Start Location 160,770
End Location 154,570,039
Largest Segment 194.8
Total Segments 194.8
So…am I correct in thinking that we share a father?
Yes you probably share a father, what are the four largest segments? See this article for how to tell a paternal half sister from an aunt
Just to be sure I don’t send the wrong info….
Chr Start Location End Location (CM) SNPs
1 9,833,878 196,262,584 180.4 22,392
1 209,864,540 247,164,683 60.2 6,236
2 58,949,304 78,861,456 21.9 2,859
2 167,181,162 242,586,061 92.5 10,466
3 36,495 44,150,891 66.9 8,075
3 149,121,730 196,464,342 63.2 6,445
4 61,566 149,825,103 151.5 17,963
4 176,034,922 191,140,682 36.2 3,065
5 91,139 7,232,551 21.0 1,777
6 148,878 73,921,917 91.0 12,071
6 128,236,166 170,663,725 61.8 7,682
7 5,439,633 8,791,785 7.4 706
7 8,833,529 32,413,455 34.8 4,820
7 112,838,024 148,659,385 38.7 4,331
8 1,874,047 6,774,191 12.7 2,018
8 137,111,315 146,241,933 16.8 1,607
10 61,055,780 135,218,153 97.9 12,237
11 2,736,546 131,636,242 146.8 19,023
12 10,635,183 16,541,935 12.0 1,120
12 91,194,904 129,817,509 67.2 7,117
13 19,572,044 27,482,648 19.2 1,889
14 18,397,823 25,681,375 18.9 1,564
15 18,436,314 34,993,795 35.1 2,654
16 1,747,724 88,668,856 127.8 13,679
17 349,593 14,115,719 40.7 3,155
17 72,545,599 75,245,670 10.9 708
19 211,912 3,318,745 10.2 630
20 58,795,786 62,352,340 11.0 789
21 16,304,787 46,897,344 62.1 5,964
22 15,437,138 49,522,492 79.1 6,321
I hope this can determine if we share a father or if I’m the aunt. The family said her grandfather had an affair with a much younger woman and a child was born so there is a chance that it could be me. Obviously I’m related, it’s just completing the puzzle that’s been so difficult.
Many many thanks!
Wow, I had that all formatted. Not sure what to say about this mess….
LOL. with four segments > 100 and matching X you share a father. CONGRATS
I’ve just had my DNA test from Ancestry and have been matched with a possible second cousin we shared 305cm and 19dna segments.
I’m searching for my mothers father she was adopted and father unknown.
We do know he was from America and that’s it.
From the DNA test we now know he was Native American that explains out skin colour as we are from London and look very Spanish/Mexican.
My question is this a good match for a second cousin she has also got English and Native American genes and a possible match to my mothers fathers side?
I’m at a total loss.
That is a solid 2nd cousin match; it could also be a half first cousin once removed or many similar relationships. What are the relative ages?
Is your mother tested?
The techniques for adoptees work here also. Read this
Also Lisa, it is good to get some paternal and mother’s maternal cousins tested to be sure the match is not on this lines. Although if there is significant native American that can be enough to sort out the matches to the unknown grandad
Thank you for replying I’ve just sent a test off for my mum so just a matter of waiting now.
If it is a second cousin match to me what would my mum match to her?
The lady I’ve matched to is my sisters age a bit of an age difference to me as my mum had me in her late 30s but definitely my siblings age.
The problem is the second cousin is adopted also and does not know her father.
We have both been matched to people who have the same surname as her biological mothers side though so hopefully we are matched through her biological mother as it will be easier to search.
A real 2nd cousin would be a first cousin once removed to your mum. You can use this calculator on shared DNA amounts and also to see relationships
Also it is the number of Gs on the shortest distance so if your mum’s grandfather(1G) is her great-grandfather (2Gs) then first (1G) once removed (difference between the number of Gs)
Thank you but this means nothing to me I’m all new to this and haven’t got a clue what it all means.
I get that she would be my mums 1st cousin one removed is she is my 2nd cousin.
As we both have Native American come up and that’s what I was testing for I’m guessing she is related to the grandfather I’m looking for but can not work out who my grandfather was as all army records don’t show if any of her family was deployed to England in around 1945 so I’m stuck.
It takes time to understand this stuff.
If other relatives on that grandad’s side have DNA tested you can eventually figure it out from the DNA. Please go to DNAadoption.com and/or read this article I mentioned to you above
I matched on ancestry.com that’s showing either he and I (I’m female) are half-siblings or 1st cousins on my father’s side. He was adopted many years back and he knew who his birth mother was. On his birth certificate she left “father” blank. My dad had 2 brother’s also. This match and I share 1533 centimorgans over 45 segments according to ancestry.com, is ancestry truly reliable in their results as I’ve read mixed reviews. This sounds like my dad because we know his history with women but still unsure. Do you think we are half-siblings? This match recently asked me to take a 23 & Me test, which I said I had no problem with. When I put in the 1533 centimorgans shared and divided it by the suggested 68, he and I would share 22.54% DNA, is that correct? Thank you.
He could be either a half sibling or a nephew as they are both 25% relationships. See
Ancestry removes some matching segments that are population specific so sometimes shows fewer cMs and more segments than if you upload your results elsewhere
If you both upload to GEDmatch or fami!y tree DNA or MyHeritage then you can compare in a chromosome browser and see how large the largest segments are and how many segments larger than 7 then compare to the charts in the above article
Thank you very much for your response. This match to me couldn’t be a nephew to me as he is either my dad’s son or one of my dad’s brother’s sons. At this time in 1951, my dad and my dad’s two brother’s lived under an hour of one another. Could this person that matched me on ancestry as close relative-1st cousin be a 1st cousin to me if he was one of my dad’s brother’s children at 1533 centimorgan’s over 45 segments of DNA? Or would he be my half-sibling? Could we be that level of centimorgans/DNA segments and still be 1st cousins by any chance in your opinion or no? I’ve seen 1st cousins go up to 1330centimorgans but on the chart you show online I see 1st cousins ending at the highest level possible more in the 1550-ish range? By the way I am younger than this match, I am 46 whereas he is 66 but my dad did have children over 4 decades so this really has me wondering. Any other input would be very appreciated.
There is no chart that I know of where a first cousin match can be that high. See
He is clearly a 25% relationship so uncle, half sib, or granddad and it sounds as if it is half sib
Gosh, thank you so much for that quick response Kitty! So very appreciated. 🙂 Have a good night and thank you again.
So I have done an Ancestry DNA tests and 23andme DNA test I have been matched to second cousins on both tests who are all matched as first cousins to each other (yay)
So we would share great grandparents as second cousins I have asked them questions and found out their grandmother had no siblings so I have narrowed it down to my grandfather being one of there grandfathers brothers.
This is where I’m stuck as all the brothers were in the army all born around the right time and I just can not find out which one came over to (London) England with the army I’ve searched and searched.
My mother was a GI baby like thousands so I’m not holding my breath in finding him.
The DNA has shown we have Native American/Mexican so I know he was definitely of this origin.
Congrats on finding your father’s family. I assume the ethnicity matches them? Now you need to find descendants of each brother and have them do a DNA test.
Also I recommend that you upload your ancestry test to familytreeDNA and MyHeritage and Gedmatch
Thank you I have uploaded to gedmatch but it makes absolutely no sense to me at all.
Yes the ethnicity matches but I’m struggling to find descendants of each brother.
Also 23andme word things differently my second cousin matches say 4.17% DNA 13segments
2.49% DNA 10segments
2.15% DNA 14segments
1.81% DNA 9segments
All of them are my second cousin matches and are matched as first cousins to each other I’ve also found out their mothers and fathers are brothers and sisters.
Try reading this post for help with GEDmatch:
Calling them second cousins by 23andme is just an estimate. Read this other post
Then use this calculator to see the possibilities (click the % to enter by percentage)
There are many possibilities, for example half first cousin and first cousin once removed
I need help with a match we share 225 centimorgans with 14 Segments. I am going around in circles. Just so confused about all of this. Thanks
I am assuming this is an ancestry match?
Put that number into the calculator at DNApainter to see the possible relationships
If your match has a tree, look at it (sometimes there is a tree on their profile. Read this blog post for how to figure a match out at ancestry
Can anyone explain this?
My brother matches CC on chromosome 20 only, at 8,942,281 to 17,622,971.
His daughter matches CC on chromosome 20 only, at 8,942,281 to 17,559,399.
Ancestry matches him at 9.2cM and her at 15.7cM
Gedmatch matches him at 16.9cM, 2035 SNP and her at 15.7cM, 1876 SNP.
My data is almost exactly the same as my brother’s and we get similar results to a 4th cousin of CC.
So the Gedmatc
Also this old post of mine shows some of the differences in total cM from GEDmatch to ancestry in my family
Ancestry removes some matching areas that it deems population specific due to pile ups.
The extra matching area for the daughter is from her mother or false see http://blog.kittycooper.com/2014/10/when-is-a-dna-segment-match-a-real-match-ibd-or-ibs-or-ibc/
If Ancestry thinks that part of the segment is unreliable, why is it deemed to be reliable for the daughter?
One of those matches is also on FtDna.It has the segment as 9,169,903 to 17,557,325
He matches me at 7.1cM Ancestry, 14.0 FtDna, 16.9 Gedmatch.
My grandfather’s closest ancestry.com match says “1st cousin” 940cMs over 35 segments. Their ages and trees leads me to believe they are true 1st cousins and other matches verify they share the same grandfather. However, I cannot verify the grandmother. With this much shared DNA, I’m assuming his grandmother is also my Grandfather’s grandmother. Would that be a valid assumption based on the DNA?
That is two much DNA for a half first cousin match so most likely the same grandmother. Either that or perhaps a sister of hers.
This calculator is very useful for looking at possible relationships:
How many centimorgans should I share with someone who shares a grandfather but not a grandmother is ,183 centimorgans to low
That’s low but possible. Look at the range for half first cousin (the designation for somone who shares one grandparent thus they have a parent who is a half sibling to your parent): https://www.thespruceeats.com/slow-cooker-lentils-3051230
Is this the wrong link?
Sure was!!! Try this
I have a match on ancestry that is 1592cm across 33 segements with the longest segment being 190cm, what would this match be?
Most likely a half sibling or a grandparent. Possibly a paternal side aunt or uncle or niece or nephew because of the size of the largest segment.
I have a question about segment size. I am helping an adoptee who has a 1st to 3rd cousin match on FamilyTreeDNA with a prediction of 2nd cousins. I have done as a “mirror tree” and know where this match fits in the tree and am trying to place the adoptee in the tree. They share 337 cM’s and the “longest block” is 129! I am wondering what you think this relationship is? They are both Jewish men who probably share the same Y-haplogroup. (one tested the Y at FamilyTreeDNA the other at 23andme.com.) Does this one very long segment mean anything significant? I have not seen this addressed anywhere!
Closer relationships share larger segments. The segments from the paternal side are also always larger. A likely relationship is half 1C where the adoptee’s father is the half sibling of the match’s father. I have not seen a 2nd cousin match with a segment thst large but in an endogamous population like AJ it is possible.
I discuss segment size in this post
Wow, I am amazed at your ability to figure this out because the father of the match did have half brothers just as you predicted! However, they were much older and already dead, so could the match be a half 1C once removed? There are possible candidates for this relationship in my “mirror tree” who are the right age. The dnapainter tools lists half 1C1R as a good possibility.
Yes that is possible although that one large segment argues for the closer relationship. If it is half 1C1R, it will likely be via the male line because of the large segment and the shared haplogroup
Further to Kalani Mondoy’s comment about the variability of size of match with more distant cousins, my brother has a match with a known half 3C1R with a total match of 139cMs, largest segment 51cMs. On Blaine Bettinger’s relationship probabilities calculator there is a 1.79% chance of this. There are always going to be these outliers.
That makes me wonder about a second distant relationship adding to the results.
Does that make sense? Could you have a cousin with a “high” shared cms number, but they be a distant cousin with multiple paths to your tree? Would the Ancestry (and maybe others) results just show a total shared cms and segments, but not be able to differentiate between a close match and a distant with two or more relatives? Is that what it looks like with issues with endogamy?
Exactly. Multiple relationships can make a match seem closer than it is since none of the companies’ relationship guesstimates take into account multiple lines. A good example are my cousins from Etne Norway where the excellent records mean all the relationships can be found… See https://blog.kittycooper.com/2014/05/etne-endogamy-and-four-generations-of-dna-for-my-norwegian-descended-cousins/
This may require a pretty simple answer, but I guess I would like to make sure I’m looking at the predicted relationships correctly.
In an unknown parent situation (yet knowing who one parent is) when looking at shared cms in Ancestry for instance, should one assume that all close relationships are half relationships, thereby skewing the DNA Painter relationships?
For instance, one side of an adoptees family has been determined, and Ancestry matches divided between paternal and maternal. The father is known. The maternal tree has been diagrammed extensively, with four close dna matches in the tree. None of these matches share any matches on the adoptees paternal side, so the assumption is they match through the mother.
The father nor any of his family is in the maternal tree.
Do you then assume that the shared cms in these four matches should be for 1/2 relationships?
I’m sorry if this is so simple. I just keep running around in circles chasing my tail.
You are not the only person who has trouble getting your head around the half relationshiop thing. Only other children by another spouse of a parent are half relationships. All the others are full relationships because you fully have that parent. For example, your Dad’s brother is your uncle, not your half uncle, as long as he is a full brother to your Dad.
Hi Kitty, thanks for the reply. Yes, I understand your example. It’s also because they share all four grand parents, right?
I need to go back and read the 1/2 relationships articles.
Ah. On my paternal side I have two half brothers, and two first cousins. They are full first cousins, not half.
That helps a great deal.
I am hoping that someone can give me an answer (although I fear I know a truth is coming I don’t want to accept). I tested my DNA on 23and me. My Father submitted his to 23and me. I wondered why neither of us was showing on each others relative list and requested a DNA comparison. It came back 0. Completely 0. Not one segment. Is there something I could have done wrong? Or…is my father not my father? I have no one else matching me closer than 3rd cousin on Mothers side. Mother insists the test is wrong. Anyone have any idea other than the obvious?
I am so sorry for your pain. Are you sure your dad elected to share his results with relatives? You could download both sets of results and then upload to another site and compare there (gedmatch, familytreeDNA, DNA.land or MyHeritage).
Just in case there is an error (very very unlikely), I suggest that you test yourself and your Dad at Ancestry as well. If your roots are American, you will likely find more matches there. Are there any relatives on your Dad’s side who might be willing to test? You could try one of them rather than your dad if asking him to do it again is a problem.
How does the ancestry composition for you look? Any surprises there too? That can also give a clue.
I don’t mean to bother you, but I wanted to know your opinion on the following match. My wife is trying to locate her father. We found two close matches on Ancestry.com and MyHeritage. One shares 197 cM across 15 segments (Ancestry.com) and the other shares 186.7 cM with 7 Shared segments, the longest at 57.9 cM (MyHeritage). They are both confirmed first cousins with extensive family trees.
We don’t know where to go from here. I believe we can rule out at least to pairs of great grandparents; her two from her mother’s side. Do you have any suggestions on what the relationship may be with two matches?
It’s never a bother, I love to help people but right now I am not very available until after the conference this weekend.
There is a methodology to follow in unknown parentage cases see
Meanwhile the likely relationships can be seen by inputting those numbers at https://dnapainter.com/tools/sharedcmv4
Look at the relative ages of your matches as compared to your wife. Most probably these are either 2nd cousins to her or 2nd cousins once removed. So if your wife is much younger, her unknown Dad might share great grandparents with those two.
Hi Kitty! I am so glad I found you! I hope you can help me answer a complicated question… I was adopted at birth with no information about my biological family other than location (Dallas). When I did my Ancestry.com and 23andme results, I come back as closely related to another woman (Mindy). We are in touch and she was also adopted and still living in Texas! We think there is a possibility that we are half siblings. We share 1,418 cM over 60 segments. We both share a significant relationship with another woman (who hasn’t responded to us) that for me is 1,903 cM over 65 segments and for Mindy 1,866 cM. 23andMe has Mindy and I listed as 1/2 sisters even though we only share 22.2% DNA. Is this possible? Does this mean that all three of us are 1/2 siblings? Thank you for any insight you can give me!
Yes it is very likely that you are half sisters. You might both get yourselves 23andme kits for Christmas to find more relatives and check if you are maternal or paternal half sisters.
Or if you both upload to GEDmatch you may be able to figure it out. If you have the same Dad you will share the entire X chromosome. See
for some more about half siblings …
I’m new to this DNA thing and having a lot of fun researching it. I have a few cousins and we’re all average cM’s and segments on my Dad’s side (his brother’s kids) but my mom’s brother’s daughter (my first cousin) and I have 1025.8 cM 36 shared segments and 81.5 longest segment. From everyone I talked to this is the highest I’ve come across for first cousins. I thought you typically had higher with your dad’s side? Why does this cousin and I have so much more? Are we pulling from more of the same relatives/ancestors? If we upload to GEDmatch will it tell us what ancestors we share?
Thank you for your time!
That is on the high end but it is in range. You have bigger segments with your Dad’s side but not necessarilly more DNA.
GEDmatch has tools for further analysis of your DNA (for example X matches) but no automatic finding of common ancestors. Only ancestry does that
I have just done a DNA test through ancestory and it matched me with a women. We share 1645 Cm across 40 segments. It matched us as close relatives-1st cousin. My father was adopted so I have reduced that I am related to this women in some way. Whoever, when I contacted her to try and figure out who she, she shut me down and said it wasn’t possible that we could be related. So my question is, who could this women be to me. Dna doesn’t lie so she must be of some relation to me, right? Maybe I just caught her by surprise or maybe she’s hiding something she doesn’t want me to know.
She could be your aunt or niece or even your father’s mother.
Now some sleuthing us in order. How old is she?
Go to DNAadoption’s mailing list for some help
Thanks for the quick response! She is 74. I am 23. My dad is 50. Going back and looking through tree she has built, she has 1 brother. Through some research I found his name. From what I know about my father’s bio mom, she was married, had an affair, and had a baby, my father. So it’s unlikely that the brother is my dads father. She gave him up and it was clear he was not her husbands(he was of mixed race) and that was that. Of course in the 60’s that was a big deal. The women I matched with has since marked her tree as locked so I cannot see it. I’m convinced she is his mother and obviously she isn’t interested in reconnecting. I’m really not either. I’m just enthralled by this whole mystery of who we are and just really wanted to at the very least know their names. If this is all I will ever find out then I guess I am okay with that. Thanks for your help and I will check the resources you have provided.
1038 cm over 43 segments came up to someone I never heard of. Any thoughts on how close this connection is?
You can always put the total cM or percentage into the calculator at DNApainter:
It says the possibilities are:
Great-Grandparent Great-Aunt / Uncle Half Aunt / Uncle 1C Half Niece / Nephew Great-Niece / Nephew Great-Grandchild
So look at the relative ages and who else among your relatives this person matches to try and figure it out
I recently came upon a relative that had 1,717 cM across 76 segments shared with me on ancestry. I have never known my father so know that this is a relative on his side since I know all the relatives on my mothers side (she has passed btw). This person cannot understand that we are probably half siblings, because the relationship doesn’t make sense to be an aunt to him or a grandparent. Am I missing another possible relationship?
Try sending them the following link
Or suggest they put that amount into the online calculator
Hi! First off, congrats for the great blog!
Not sure if this makes sense, but I have 2 raw files and I’m trying to use Excel to calculate how much DNA they share (the last 2 columns are the results for person 1 and person 2, respectively).
rs10907177 1 1021346 AA AA
rs3737728 1 1021415 — AG
rs10907178 1 1021583 AA AA
rs9442398 1 1021695 AG —
rs9442400 1 1025301 TC CC
What threshold should I use to determine that a set of consecutive rows with the same results is long enough to be considered a shared sequence?
And what is a cM in this context? Is each row a cM?
Or is this not a good approach whatsoever? Thank you!
That sounds like too much work. I would just upload them both to Gedmatch genesis and do a one to one compare. If you are uncomfortable with Gedmatch being somewhat public , you can mark both kits as research, then only you can see them
Definitely, thank you.
However, from an educational standpoint, I would love to understand how these sites scan the files. For example, I read that a “sequence” for 23andme is a contiguous region of 700+ matching SNPs and 7+ cMs. If I scan my files and I see several matching rows, and then I run into a “flipped” result (e.g. AG GA) would I stop counting and stop the sequence, or would that be considered part of it and I should keep counting?
Unfortunately I haven’t been able to find any open paper that describes how these algorithms work.
See what you can find on this page
Else contact Tim Janzen, he can probably answer this and is acitve in the rootsweb mailing list group – so try there firstname.lastname@example.org
My bio sister and I are very close matches with a man who had been adopted and has no blood relatives. Facts show that the man is related to my deceased father’s maternal side of the family; my father was an only child.
My sister, CE, has 465 Cm and 26 segments with this man, while I, MK, have 333 Cm and 23 segments with the man. In studying our chromosome similarities, CE and man share 9 segments that are length from 20-44 long. Myself, MK and man share 5 segments that are length 20-33 long. And most interesting is that the 3 of us share exact (or almost exact) segments on chromosomes 5, 8, and 11.
We are trying to figure out where this man fits into our family. I’m feeling that this data is significant but I don’t quite know how. Please let me know your thoughts!!
Thanks very much!!!
What I do is average the two sisters and look up 399 cM. Using the calculator at https://dnapainter.com/tools/sharedcmv4 shows that half great uncle would fit (your paternal grandmother’s half brother), but so would half first cousin and first cousin once removed (or half). In the latter case your father would have a half maternal sibling he did not know existed.
So can you get more relatives on your father’s maternal side to test? Does his age fit either hypothesis? If you can get more testers you can try the what are the odds tool
Hi Kitty, thanks for the response. You confirmed my suspicions of the 2 possible scenarios….which is very helpful to know we r on the right track. My grandmother had 5 siblings. Of those siblings’ descendants, their dna % with this adopted male blood relative was 2.88% while another was 5.22% (which is close to my sisters and mine with adoptee).
Out of both of your 2 scenarios, the first one is impossible since those ancestors had been deceased prior to 1954 when adoptee was born. The 2nd scenario is indeed possible. We are trying to get a dna comparison with my deceased dad and adoptee, however, my dad’s dna is on ancestry and ftdna and the adoptee’s dna is on 23andme, so my sister is having difficulty comparing them.
Additionally, my sister has my grandmother’s old lipsticks. It was my sister’s idea that maybe the lipsticks contain some of my grandma’s dna that can be tested. What are your thoughts?
Thx very much!!
The way to compare ftDNA and 23and me is to upload the results to a third site that takes those. Gedmatch GENESIS is best for that. Family tree DNA is supposed to accept 23and me uploads and if that is not working contact customer support. Lastly My heritage upstairs both but there is an extra fee to unlock the DNA too!s
I doubt lipstick would have enough DNA but do you have any old letters she sent? Licked stamps and envelope flaps can be used. There is an Australian company that does that, to the letter, https://www.totheletterdna.com/envelopes-faqs
And myheritage will be announcing something similar later this year
Thank you so much Kitty for all your fine suggestions. I will look into them to pursue our next steps.
So I’ve just done a DNA test on Ancestry, and there was only one match within 2nd cousin range. 377 cms across 25 segments. I’ve looked at the possibilities on the chart already. But I just wanted to ask your opinion.
This person has a family tree with names I don’t recognise. Unfortunately one surname my grandmother did recognise. I say unfortunately because this surname is linked with a not-so-great memory from about 45 years ago. There’s been a bit of mystery as to who my mother’s biological father is, as it is out of two people. The match is “most likely a second cousin”, but I’m next to certain they are either a half-first cousin 1x removed or a half-aunt. Are either of those more probable than the other? I’ve made my mum order a DNA test and that will tell if they are her half-sister or half-first cousin, if at all. My match isn’t especially interested in knowing but she’s so closely related and next to no matches thus far have been from mum’s side, plus it might put my grandmother’s mind to rest rather than keeping her guessing.
It’s a bit of a messy situation but I don’t intend on sharing this information with my mother per grandmother’s wishes.
Thanks so much for the post
Use the online calculator here:
And you can see 1st cousin once removed is more likely than the others. If the brother or sister of the bad memory is the parent of your match then the match is a FULL first cousin once removed to you. The half only comes in when the person in question is descended from a half sibling of your ancestor.
My bad! I’m a bit slack with the rules of basic relationships apparently. Thanks for replying so quickly. It seems 1c1r is more than likely the answer. There must have been a brother.
That calculator’s great by the way.
Hi I have paper trails for all of my 2 great grandparents and most of my 3 great grandparents. When I come across a cousin who matches my paper trail I try to confirm that with a DNA match. Lately I have been unable to confirm because they do not have at least one matching 7 cM segment. As I look further into it I find that they have several 3+ segments for usually a total of 25-35 cM. As I understand it segment lengths get shorter as genetic distance gets longer so it would make sense that more distant cousins would have shorter matching segment lengths. So what am I missing or where did I go wrong?
Segments smaller than 7cM are so often false that most of us just ignore them no matter how many you have with a match. People who have many small segment matches with you are likely from the same population group but not closely related.
In other words, you will almost never be able to connect a DNA relative to your paper trail when all their matching segments are all less than 6cM. There are rare exceptions for triangulating segments.
here is a case from my family: https://blog.kittycooper.com/2016/03/another-triangulation-success-another-etne-cousin/
I am adopted I have one close family match.. She is either my half sister or my aunt. We share 1940 centimorgand across 58 segments.. The family rumours we either have the same dad or she is my aunt.. She is the only living family memeber left.. How do we know what we are???
If you are sisters with the same father you will share a full X chromosome (be sure to check the box prevent hard breaks). See
However it is possible that an aunt and a niece can share a full X, so if you do share the X, then next you need to look at segment sizes see:
My family is mostly highly endogamous (Armenians) and my top match on myheritage was an Armenian with total 69.1 cM (segments 26.9, 22.8, 9.9, 9.5) or 1% DNA, yet I could not recognize any of their surnames and neither could my match recognize any of of mine. Also, it appears that my match has no known link to my country of birth although had links to neighboring countries. I was told many times by my parents on different occasionas that I was a mixed bag (never clarified exactly how, since my mom is the only one being 1/4 non-Armenian or Russian) so I suspected I may have been adopted at birth. I tried to connect these dots possible dots with the fact that I cannot recognize the top Armenian match surnames and vice versa, but also keeping in mind the endogamy at play so feeling kinda puzzled. A few days ago another match popped up on myheritage and now takes the leading spot. This match is from Norway (appears to be Norwegian based on surname with possibility of being part Armenian through 14% west asian indicated in their profile). This match shares 1.1% DNA with total 78.1 cM (30.3, 21.5, 18, 8.3). To make matters more complicated, I have a match on FtDNA that is a known 2nd cousin to my father. The match there shares 157.1 cM (38.85, 32.70, 21.78, 20.81, 16.91, 14.83, 11.22). Her daughter popped up at 79 cM across 6 segments on Ancestry before she asked her mom to transfer to FtDNA upon my suggestion. Mother has non-Armenian surnames (non-Norwegian too) in her tree while the daughter has even more non-Armenian surnames (non-Norwegian) in addition through her father’s line. Some adopted people suggested a secret half-sibling relationship to me, but I am not sure. My father and brother are not really interested or enthusiastic to submit these kinds of tests. And that’s on the top of the fact that we know very little about my paternal grandfather’s line (we know only two surnames through that line). I tried to use that fact to convince them to test, but no luck. I do not want to push it, especially if there is something that I am unaware of regarding myself. The bottom line is do you think the Norwegian match can provide clues or are those large segments “sticky” segments and that means the match is like the Armenian one (up to 10th cousin in distance)? Do not know much about Norwegians, whether they are endogamous or not. I am waiting to get approval from the that match to view their tree…
Some areas of Norway are a bit interrelated and others are not. Nothing like Armenians, Lebanese, or Jewish. What I see in Norway is a number of cousins who are my 5th and/or 6th cousin two or three times, whereas in a truly endogamous group you see the same ancestor multiple times due to many cousin marriages.
Since you match your father’s 2nd cousin for the expected amount, I would not worry about being adopted. Maybe someone up his line was adopted or did not have the expected father but you would need more family to test to figure it out.
Notice that you have 7 segments > 10cM with your 2nd1R. Endogamy is marked by sharing many small 6-8 cM segments. My current rule of thumb for a genealogically relevant endagamous match is one segment > 20 cM and another > 10 cM in a group of 5 or so segments. Another thing I do with endogamous matches is remove 10% of the total cM (total the segments 7cM and larger) and then look it up at
Try to get all your matches to upload to GEDmatch so you can compare them to each other. Remember that any match whom you share less than about 100cM with can be a more distant cousin than they seem, especially when endogamy is involved.
Thanks for your reply, Kitty. I would like to add that the Norwegian match shows only one “common” match (from US) and there are only 12 people from Norway reported as matches to me. Did I hit the very low probability with this closer match? Or are there simply not enough people testing yet in that country?
Martin, How much Norwegian do you have? There are plenty of tested Norwegians, not nearly as plentiful as Americans though. Initially I had better luck finding them at 23andme but now more are also testing on MyHeritage. I really recommend you test at 23andme where you can get a segment by segment breakdown of your ethnicity, see
Haha will save up for 23andme and test there for sure. Thanks for this suggestion!
I am not sure if they accept free dna raw transfers like ftdna and myheritage do. Regarding ethnic composition, the 3 sites show somewhat different results. Ftdna shows almost a half of southeast Europe (Balkan region), the rest asia minor with a tiny bit of east Asian. Ancestry shows less than half of caucasus with about 20% of middle eastern and Persia, and less than 10% each for Greece, eastern europe, finland, and Baltic. MyHeritage shows half of west asia with rest being less than 5% each for middle eastern and Irish, Scottish, welsh, but over 30% Greek/Italian. As you can see, ftdna and myheritage do not show any northeastern or central north European and percentages vary. I am pretty skeptical about these estimates to be honest, so I try to mostly pay attention to matches, trees and surnames. On ancestry I do not have genetic communities or connections to any subregions either. Some friends of mine complained that ancestry, even after its latest update, showed very little or even 0% of one of their parent’s 100% documented ethnicity/region.
I was wondering if you can help. My husbands DNA made a match as a Close Family member on ancestry.com. I inputed the information to gedmatch.com. This is what I see. I have no clue whether she is a first cousin or an aunt.
Largest segment = 107.4 cM
Total Half-Match segments (HIR) = 1537.5 cM (42.871 Pct)
Estimated number of generations to MRCA = 1.6
43 shared segments found for this comparison.
423696 SNPs used for this comparison.
58.349 Pct SNPs are full identical
I have been searching for my father for 20 years (since i was 13) and I took an ancestry DNA test a couple years ago but just recently have had a match pop up. we share 1341cM across 48 segments. I don’t know exactly what this means besides it puts him in the range of a half sibling to a first cousin. Is there any way to chase this further if I am unable to contact him since he doesn’t appear to have an active account? I have sent him a couple messages but the first message shows read. Any thoughts or ideas would be a great help.
He is most likely a half nephew or half brother. Plug the number into https://dnapainter.com/tools/sharedcmv4 to see that …
If his name shows then you can google him
Try the techniques in this post
Careful in how you contact him as this could be a shock to his family. Example here: https://dnaadoption.org/email-to-close-match/
I’ve gotten a predicted relationship from Ancestry.com for a 1st cousin. It shows a shared DNA of 1599 cM across 46 segments. That seems to fit for a 1st cousin but we can’t find links to verify since she has limited family info due to adoption and I am ion a similar situation. Do you have any suggestions where we should start?
That amount of shared DNA is too high for a first cousin. More likely she is a niece/aunt or even a half sibling. Look to see which other relatives of yours she matches, your father’s or mother’s side? If she matches both sides, then she is likely the child of one of your siblings. Get more family members to test if you can and ask around. She is close family to you. How far apart are you in age? That is also a clue.
i am pretty new to this DNA matching, even though had my own, my mothers, and a few other family tested a while ago. I recently strated properly, and contacted matches to my family. I wasnt aware of the difficulty of matching 3rd-5th cousins, and managed to do 2 this week, because my paper trail is pretty good. Then i started trying to learn more, especially about how to reconstruct earlier ancestors Chromosomes. And the best ways to work on DNA. I think I could do with a good book, or two, recomendations on web links, software ( machine based and online), and are there any good courses in the uk? I have played with DNA painter, and read many bits of your work Kitty. Help most appreciated, Bill
The software I am currently using the most is the Genetic Affairs clustering with tree building, see
There are lots of good presentations online, from the recent RootsTech: https://www.rootstech.org/category/2020-rootstech-sessions
and not free but worthwhile http://i4gg.org/conference-videos/
For good books see the list in my Newbie FAQ
Or for a more advanced book perhaps Debbie Parker Wayne’s Advanced Genetic Genealogy: Techniques and Case Studies: https://tinyurl.com/sh42og3
And in England I would recommend Debbie Kennet, her site is at: https://cruwys.blogspot.com/
or over in Ireland Maurice Gleason – lots of youtube videos like this one:
If there is 19 locus’ compared and there are 12 that are identical (not including double variations of the same allele for instance 16 17 and 16 17 or 10 10) and all of the centimorgans are above 9cm up to 17cm what is the relationship? Are we related? Please help me.
15 18 15 16
16 17 16 17
12 12 12 13
10 11 10 12
11 11 8 11
10 12 13 13
30 30.2 29 29
12 16 13 17
10 11 14 15
14 14 14 16
7 9.3 6 9.3
21 21 20 22
15 16 11 15
11 12 12 12
11 12 11 12
10 10 10 10
17 27.2 14 19
13 14 13 16
16 17 20 21
My expertise is for the personal genome tests like Ancestry DNA, not for paternity style relatedness tests which test fewer SNPs. Ask the vendor of your test what it means.
I have a match through Ancestry that says:
2,314 cM across 61 segments
For a match to a woman that says is my sister
Please help me understand if that number is a strong match. I have been searching for my biological family for over 50 years.
Congratulations Christi, your search may be over. She is most likely your full sister but could also be a garnadparent or grandchild or a half sibling. Screenshot her tree and information and then get in touch carefully. Lots of help for adoptees at DNAadoption and see my page here:
Thank You SO MUCH! She actually was in touch with me first. I show up on hers as well. It has just been so long that it feels too good to be true! I greatly appreciate your response!
Just wanted to share good news with everyone here. AncestryDNA will FINALLY show the Largest segment you share with your matches in their upcoming update scheduled for the beginning of August. Just saw this note in my account. Isn’t that amazing? I mean for AncestryDNA this is a bit unheard of. Glad people put enough pressure to make them add a little bit of something in this department. They still won’t include a chromosome browser, but your matches below the total of 8 cM shared dna may disappear. Also your total number of segments you share with matches may change, but the total shared dna will likely remain the same.
I think the update will help me get some clues on some of my countless endogamous matches in their database!
I am not sure exactly why it may be a good thing to get rid of matches in the 6-7 cM range. Some of us are trying to peace out possible long-lost remote tree connections with those matches. I have a free account with them so I am unable to start messaging those matches in the hopes of keeping them. My main concern is not really losing the matches but the potential to have legit matches less than 8 cM overlooked. I already have at least 5 matches in that range that are legitimate based on our mutual analysis. If we lose future matches that can provide clues to our distant past – say beyond 4-5 generations – what is the point of trying to work harder to find out more? Not to mention that Ancestry tends to round the matches from 7.5cM to 8cM up to 8 cM. Will those matches be lost as well even if they show exactly 8 cM? It would be better if they revise their Timber algorithm instead of erasing the matches that we may need. This update sounds kinda ridiculous.
Many of us users who have thousands of false matches due to endogamy welcome these changes.
Small matches to distant cousins may not even be from the known ancestor. Read what Blaine Bettinger has to say about that here: https://thegeneticgenealogist.com/2020/07/17/losing-distant-matches-at-ancestrydna/
Yes this is really great news Rudy, and thank you for mentioning it. it seems I am one of the few bloggers to not yet post about it.
But will they let us sort by largest segment? Those of us with endogamy like to use that sort at GEDmatch
Hey Kitty. I dropped by my account after having read Rudy’s notice. I hope they do sort by the longest segment (myheritage is way ahead in those filters) but that would not answer the question of how they plan to keep the same total cM and adjust the number of segments. How would that work for endogamous matches? If they have small segments either they get even smaller or the larger ones do while new ones pop out in order for the total number of segments to increase. Or if they are taking down some segments they have to make the other ones larger. Myheritage simply changed total shared dna amount when they updated their system. Some matches went all the way down or disappeared entirely. Ancestry says the relationship prediction will be unchanged as well.
Ancestry has always been a mysterious one when it came to making big decisions. I am partly Jewish with mostly Pakistani background. Some of my matches are endogamous while others are not. I think it would not matter for me personally if they delete the small matches, especially the endogamous ones. I cannot find genealogical connection with most of my distant matches no matter how hard I try. Ancestry could customize accounts based on surveys taken, so that those who do not need questionable matches could opt in to have them removed. DNA is a complex issue and definitely does not apply to everyone equally.
I am an illegitimate child and my mother is no help. I convinced her and my siblings to take an ancestry test and I matched to a few 1st-2nd cousins all on my dad’s side. One that populated under close relatives is a man in his mid 60’s 669cM across 24 segments and the longest segment is 120cM. What does this longest segment mean? He says based on our age gap (I’m 31) he believes he may be a second cousin but I’m thinking it may be closer. Any advice?
I have always preferred the term “love child”
He is definitely a close relation. Likely a first cousin or a half uncle. Ask him if he has a half brother, if so that might be your father. The Age difference suggests he is one generation older than you but that is not for sure. The largest segment suggests a close relationship, ie half uncle. Use this calculator to see the likely relationships:
With so many close Paternal matches building a tree for them should help you figure it out. See
Thank you. I responded to him with your question. I started the family tree but it’s 10 kids from the grandmother and I became very over whelmed and quit. I will have to pick it up again.
Tested with my brother and just as I suspected we are half sibs, (1874cM, 47 segments, longest seg 155)
confronted my mother when I figured out my bio father, she confirmed
Through testing found that I have a 1/2 sister (1725cM, 34 segments, longest seg 175) is this correct?
Her daughters- 834 cM 29 seg, longest 90
760 cM 23seg longest 59
Also found a half brother who did not test but has since died but based on location and history and his daughters DNA testing.
Here lists his daughters results
1246 cM 26 seg longest 143
985 cM 20seg longest 90
571 cM 17 seg longest 97
So here are my questions, I have accurately identified the sibs as half?
These daughters are half nieces?
Read your article on X chromosomes, but don’t think I can input the information for the 1/2 sister to see if we have the blue line.
Do I understand that the longest cM segments indicates same common ancestor?
Yes you have found two half siblings. If you and your half sister upload to GEDmatch you can see that blue line when you compare your X chromosomes.
The only incorrect assumption in your comment is the longest segment. Having a large longest segment just indicates a close relationship. Triangulation, where three people all share a specific segment with each other, is indicative of a common ancestor see https://blog.kittycooper.com/2015/02/triangulation-proving-a-common-ancestor/
Thank you, Kitty. Your information and charts are extremely helpful.
Hey I noticed Ancestry shows longest segment now. It is great. But then I noticed that when there are 2 segments, the second segment is as little as 2-3 cM. Anyone else noticed that?
Why would they keep these tiny segments when they could be false at that level? Again, I would not have known this before the update. It looks awfully like ftdna matches now. MyHeritage does not show anything less than 6 cM when there are multiple segments. Any thoughts on these tiny segments on ancestry?
The size of the longest segment is before they apply their algorithm that removes poplution specific DNA so it can be far larger than the segment that is listed as one of two. Look at some of your one segment matches to see this. The other segment is not 2-3 but at least 6 cM….
I have a blog post in progree on this
Thank you Kitty. Great to know. I did notice this with single segments! That is quite interesting, as I have not seen the feature in other services. Please do share the link when your article becomes available! Thanks a lot.
I wrote the article last week, here is the link:
Can a 65.4 cM endogamous match with only 2 segments, largest being 35.7 cM, be more distant than predicted 3rd-4th cousin on MyHeritage?
Yes it can be further back than that but 35.7 is large enough to think 3rd/4th cousin might be accurate.
One expects 5 or 6 segments at least in an endogamous community match but perhaps this person has only one grand parent or great grandparent from your endogamous community …
The other thing I have seen is double 5th/6th cousin with each segment from a different distant ancestor in the line of that one endogamous grandparent. But then the segments are usually smaller, however if your kits are from different companies then those segment sizes may only be approximations.
to see the possibilities. Then try again with 10% removed to see what they might be when endogamous.
Thank you for the detailed info, Kitty!
Yes, I think most of these types are extremely distant no matter the segment size it seems…
I am wondering, is it at all typical that matches like these do not have any shared matches? This lone match was excluded on clustering report for this reason. My other endogamous match, though with 4 segments and total 80 cM, was also excluded and had only one shared match. Wondering why this is. Are all endogamous matches usually on their own?
I would upload to GEDmatch and analyze that chromosome further with the matching segment tool and the triangulation tool. Ask your 35 cM match to do the same.
One probem is that many of the kits on MyHeritage are uploads and thus tests with different sets of SNPs so the imputation at MyHertage might possibly make two smaller segments seem to be one larger one.
Great to know, Kitty. So, to bypass these discrepancies with uploads from different companies, one needs to be a 2nd cousin and closer by prediction?
No. The only way to truly bypass the discrepancies is to test at the same company as your match and even then chips change … for the endogamous having large segments matters, usually yes, a 2nd cousin prediction.
The reason those matches were on their own was because no other match met the criteria for inclusion in the cluster report. Go to the match page and click on that match and look at the shared matches to see if they shed light on the relationshiop
After about 4-5 months his uncle (or half-brother but there is about 20-year difference between them) popped up on my list. Interestingly, his uncle shares only 50.7 cM with 3 segments – largest 37.4 cM and two others each below 7 cM (and the nephew shares 65.4 cM with two segments, largest 35.7 cM). I am so confused. If we ignore the two below 7 cM for the uncle then he shares about half of his nephew! Shouldn’t it be the other way around? The two are endogamous people (Armenians based on their genetic group hints).
If this is an unusual case I would love to hear your expert opinion on this. I know you mentioned chip differences above, but can that interfere so much as to twist the shared dna backwards for two people of different generations?
That sounds like one segment you share with this match is from his paternal side and the other his maternal side since the match to the uncle who shares only one of those lines is smaller. I presume the 37cM segment is the same with you for both of them?
Yes, I just checked the chromosome browser, the uncle and nephew share 35.7 block only. Wow, so it is possible to share another block (29.7 cM) from another line for the nephew? Just wow. I thought those blocks would be way smaller if coming from multiple lines. I guess it is really blurry when you are less than 100 cM shared dna with someone. I guess from this experience the endogamous common ancestor can be as far back as 6th cousins or even further back. They do not reply so no way of knowing..yet)
I had a person contact me on Ancestry who said she was an abandoned baby and was searching for biological parents. She believes she has found her maternal line, but not her paternal. She has a 10 cM across 1 segments match with me, but not my other sibling. Ancestry says 5-8th cousin. There are no shared surnames with any of the research she has done in her possible trees. How valid is this match?
Ruth, that match can be from pretty far back in time so unlikely to be of much help to her but yes it is valid even if possible hundreds of years back
I have a male cousin and we know we share a Grandmother but much research has shown we may also share a Grandfather. Our DNA matches as 10% shared DNA 707cm across 30 segments with the longest segment being 68cm. Is this conclusive either way.
Sorry not to get back to you sooner. You asked this question on the day my husband died … so I did not see it.
If you use DNApainter’s tool you will see that it is 70% a 1st cousin or 30% a half first cousin …
The definitive way to tell is find cousins descended from the grandfather’s parents and see if they match your cousin too
I am so sorry to have asked my question in my earlier reply without knowing of your husband’s loss.. Please accept my sincere condolences. You are a tremendous gift to our dna world. Thank you for your posts, as always. Please do not rush on replies if you need time to recuperate.
I am a male. I know (strongly believe) that a full brother-sister pair are related to me as half cousins. One of the brother-sister pair (the male) matches with me at 159cm across 10 segments. The other brother-sister pair (the female) matches with me at only 43cm across 3 segments. In predicting the likely degree of cousin relationship that I have with this pair, should I trust more the higher match or should I not be any more confident in predicting the relationship from any of the two results? Apologies if a similar version of this question has been previously asked.
Those numbers are too low for half first cousins. Use this calculator
That being said, where did you test? did you mean half 2nd cousins? (more likely)
Kitty: I made no mention of First cousin in my query. I believe that my imputed (our family is unsure) biological great grandfather (but not my great grandmother) is also the great, great grandparent of the brother sister pair. If true, this would mean a half 2nd cousin, 1X removed relationship with them. Correct? This relationship makes sense in terms of the male sibling results. However, the female sibling results seem extremely low for such an imputed relationship. I understand that as connections get lower and more tenuous, it becomes harder to make an imputation. Thus, I have been trusting more the larger male sibling results, than the lower female sibling results, in making the imputation to the presumed common ancestor. Is this valid? Does it make sense to trust more the higher shared CM (with the male sibling) than the much lower shared CM (with the female sibling) to consequently make a half 2nd cousin, 1X removed imputation?
BTW. You do great work! Thanks much.
Non genealogists usually mean 1st cousin when they say cousin … so thanks for clarifying
When I have 2 siblings with such different amounts shared, after checking that they are full siblings, I usually average the two and use that number for lookups.
However once you get past close family there is more and more variance so best to see who else they match and how much (that can only be done at 23andme or GEDmatch although MyHeritage will show in the list of matching relatives what there match to the other is.
and thank you
Hello Kitty: I have an image on one page of my website at https://www.adkins.ws/individual.php?pid=I17170 … this page represents my 3rd great-grandfather, (given name unknown) McDermott. Please note the image entitled “McDermott DNA match autocluster.” I also list on the page a number of genetic cousins, who I have determined, based on this autocluster & other data, to all be direct descendants of my ggg-grand. Am I interpreting this data correctly? Thanks for your comments.
HI Kitty. I have a match. It matches to my father’s side but the match has no matching surnames in their tree. The match is 74cm with 8 shared segments the longest being 47. Would you say this could be a second cousin?
Possibly or maybe a 3rd. Use the calculator here https://dnapainter.com/tools/sharedcmv4
To see the possibilities.
And Yes that large segment suggests its somewhat close. One of you may have a misattributed parentage case in your tree or a name change …
I have matched with someone on Ancestry. 627CM across 28 segments. Longest segment is 57CM.
Could this be a first cousin?
Angela, according to DNApainter’s calculator, 1C is only 30% so yes it could be but there are many other possibilities
plus the longest segment is on the small side for a first cousin. More likely a 1C1R … look at the age and the other matches
Thanks Kitty, it’s a little confusing as this person matchrd with my 17 year old son as well. 418CM over 21 segments. Longest segment 40cm.
Hi Kitty, My 17 year old son (whose father is 53 and adopted) has matched with a gentleman on Ancestry who is also 53. He comes in at 110cm across 4 segments. Longest segment is 78cm. Do you think this could be a second or third cousin?
Thanks for the blog and all info provided. I’m adopted and looking for my birth father and I’m really close as I believe I’ve nailed down the family. I have a match “Erin” at 787cm longest 75cm and another match “Yvette”(also adopted) at 726cm longest 94cm. I’ve spoken to both and found that they match at 1198cm (didn’t get longest). Before “Yvette” tested I thought maybe myself and “Erin” were first cousins and that my father should be one of her uncles…although the ages of all her uncles did not work with the little(and only info) I had on my father which was his approx birth year. They were all at least 20+ yrs older. Does the fact that Erin and Yvette match a lot closer than I do with either of them prove that I may be one generation down from them? This would be really helpful in knowing so I can focus the search on a different generation.
By the way I match at 389cm longest 51cm with Erin’s daughter.
Thanks for any thoughts you may have.
All those are in range for first cousins. Use this calculator to see that https://dnapainter.com/tools/sharedcmv4
Another possibility is that your father was their first cousin, if the ages work, so you are a first cousin once remoeved to them
So do Yvette and Erin know how they are related? Likely their common grandparents or are also yours or your father’s
Thanks for your response Kitty. No they do not know how they’re related—Yvette only recently found out her father is not who she thought it was(long story) so she tested on Ancestry and found out she was very closely related to Erin. Her father is likely one of Erin’s uncles(there’s alot so still trying to figure out who)They are both in the early to mid 60’s —I’m 48. I understand I could be 1st cousins to both I thought maybe since they are a much higher match to eachother than I am to both of them it possibly meant I’m a generation below them? Not sure if that makes sense?
Yes you could be either the same generation or one generation later. Erin and Yvette could also be half siblings with that amount of shared DNA. If they are both female and both upload to GEDmatch.com, they can check if they match for the complete X chromosome, which sisters who share a father will… see http://blog.kittycooper.com/2014/03/how-can-the-x-chromosome-help-with-maternal-versus-paternal/
Oh wow. I didn’t think that was enough to be half siblings. They are both female so I’ll have them upload to GEDmatch to check. Thanks so much for your help!
I have a recent match with a previously unknown to me individual (male) that was validated on both 23&Me and Ancestry as a likely 1st cousin relationship. The individual being noted as likely 1st cousin is 20 years my junior in age. I am 52 and he is 32.
I have a very small family in this country and aside from my now deceased father, the only family that resides, or has ever resided in country is from my Mom’s side, i.e. her now deceased parents and her still living brother and his family which includes two known 1st cousins from his current marriage.
Here is my question. Is it possible for this potential 1st cousin or potential half uncle originating from my Mom’s parents side of the family to share the same paternal Haplogroup (E-V13) as myself? We share different maternal Haplogroups. If it helps, my ancestry is largely German. My mother, father and grandparents on both sides were all born in Germany, but from different regions.
I realize also that based on shared cm that a half niece or nephew is also a possibility, so just looking to try and refine the likely connection here given it is unlikely other family members will do the testing. Basically, I’m trying to determine how likely he is the son of my grandfather with another woman not my grandmother, or the son of my uncle outside of his current marriage, or the son of a potential half brother my Dad may have sired outside of his marriage to my Mom. This is what I narrowed it down to given our ages and family locations.
For further reference, here are the details from 23&Me and Ancestry:
23&Me: 933cm/12.53% shared DNA across 25 segments. Longest segment of 107.27cm. Some others in the 70cm, 60cm and 50cm ranges.
Ancestry: 937cm/13% shared DNA across 27 segments. Longest segment of 107cm.
Please let me know your thoughts based on the DNA details and if there is any other information that I may have missed providing that would be useful to you.
Those large segments argue for a closer relationship. My guess would be the son of your unknown half brother from your father. Are you in touch with him?What does he know of his parentage?
That haplogroup. a subset of the group known as E1b1b in the previous nomenclature is not that rare in central europe so may or may not be significant. See
If you both do the Y37 test at family tree DNA (on sale til Friday), it could prove that you share a recent paternal line.
Best would be if you get get cousins on both sides to test. I will email you privately.
Thanks for the response Kitty and additional insights. I am in touch with him and we have shared some recent family histories. It’s a bit too long to detail here so I’ll send separately.
There are some ‘logistics’ reasons that would point to him being more directly linked to my grandfather or uncle than my Father in paternal lines, but I don’t discount any of the possibilities. I was also unclear and could not find any info that clearly addressed whether my paternal haplogroup question was even feasible. Appreciate you answering that also.
I have found a match on MyHeritage with a (previously unknown) male person:
Total 145.4cM, 9 Shared segments, largest segment 33.8 cM.
His match with my brother is:
Total 108cM, 8 shared segments, largest 24.9cM.
There are no known relationships in my fairly well documented tree, or his (we have been in communication), that would account for this connection, so I believe it is through an unacknowledged relationship.
I have many DNA matches that can be attributed to my maternal ancestors, and my father’s maternal line but little of significance as expected from my father’s paternal line. I have some other evidence that suggests my father’s documented father was not necessarily his biological father.
We are all in our 70’s (me, my brother, and X).
I assume that the size of the largest segments suggest a relatively recent connection. Do you have any insights on areas to follow up?
Also have a look at the action items in this article about a similar puzzle in my tree
Try clustering and ask your match to run a cluster also to see what other matches are shared with each other to narrow this down.
Also try a Y 37 marker test at family tree DNA to see if it turns up a surname since you suspect the break is your paternal grandad.
Thanks Kitty for your suggestions.
My father was born in the US in 1898. The primary match, X, lives in Germany, with no obvious connections. He did have great uncles who were in the US and of ‘eligible age’ at that time – which might be about the right DNA match level? Again, there are no significant matches on surnames etc.
In MyHeritage there are only 2 others in the cluster with X – a brother and half sister (common father) (brother 37cM with me, 53cM with X) – but again no obvious/documented connection – live in Sweden, unknown to each other.
I’ll keep digging, thanks!
See if he can put you in touch with any of the descendants of those great uncles so you can get them to test. He could easily be your 2nd cousin once removed with those numbers or even just a 2nd cousin, thus one of those great uncles would be your grandad
One problem is that very few Germans have tested, so you need to search for people to test which will solve this for you
Thanks Kitty – will give that a try.
I’ve got 25 shared segments with a DNA match but they are all less than 6cM. Can this many segments with a total of 94cM all be false matches?
Yes, this is not a good match. They can all be false or at least from so far back that you will not find the many ancestors they are from. This would be typical of a match in an endogamous population.
I want to thank you for all of your help over the years! You have helped me solve 2 birth father searches so far!
I am a volunteer search angel & have been working on a birth father search without success for about two years. We have had help from many experts but still have no answers & even the experts have given up!
So I’m starting over with the basics- her closest match.
She is about 52 & the match is 82. They match 1212cM’s on AncestryDNA with 35 segments shared.
1197cM shared & the 4 largest are: 100.9, 94.8, 87.1, 61.6
estimated # of generations to MRCA=1.8
on the X-3 segments shared, the largest is 105cM for a total of 169.6cM
I have used many of the DNA relationship tools & they say probably a half aunt but could be full aunt or 1st cousin. The problem with half aunt & 1st cousin is that all the closest DNA matches fit in our research tree & are related to this match.
Can you help?
I will email you