How to tell the relationship from the shared DNA

Many people have the illusion that if their testing company says a person is a 3rd to 5th cousin they really will be. That is not the case.

The testing companies are just making the best guess they can from the data they have. They do not seem to take segment sizes into account, rather they primarily use total shared DNA measured in centimorgans (cMs) for their relatedness estimates, usually the sum of all matching segments of 5 cM or larger. Close relatives will always share larger chunks with each other and so size does matter here.

Recently I have received numerous questions from people trying to figure out if a new match is a half sibling or a niece or a grandchild. These are hard to tell apart without testing more relatives as they all share about 25% of their DNA with each other. So I decided to collect some detailed statistics on those specific relationships with a google form (click here) that includes total segments and segment sizes for a future blog post [UPDATE as of sept 2017: First round results are written up at https://blog.kittycooper.com/2017/09/the-25-relationship-a-first-look-at-the-data/ ]

The companies predict reasonably well for close family but it is just not possible to be accurate beyond that due to the randomness of DNA inheritance.

For example, here is a picture from the new 23andme of some of the DNA I share with Dick, a 2nd cousin on Dad’s paternal side so blue, and John, a 2nd cousin on Dad’s maternal side so red.

Ktty2ndCousinsS

I share a third again as much DNA with John as I do with Dick,  even excluding the 14 cM on the X. The expected amount for a 2nd cousin is 3.125% which is 212.50 cM, right in the middle between these two.
Henry2nds Checking my brother, I see the same effect – he has 282 cM with John versus 185 with Dick. Not surprisingly, when I look at Dad I find that he shares almost twice as much with John as with Dick. Clearly he just inherited more of the same DNA as John’s mother from their common grandparents. Conversely, he inherited less DNA shared with Dick’s mother from his other grandparents.

On the left is a comparison of my first cousin Henry with both Dick and John. The amount he shares with each 2nd cousin is practically identical, as long as you subtract the 40 cM that he shares with John on the X from the total shown by 23andme. Amazing how variable DNA inheritance can be among 2nd cousins.

Click here for the ISOGG wiki article on Autosomal DNA statistics which usually includes the current chart from Blaine Bettinger’s shared centimorgan DNA project.

Personally I have his chart (shown below, click it for a larger version) bookmarked for easy reference. I rely on it heavily.

SharedcMProjectSmll

Warning, Ancestry.com DNA testing will show a smaller number of matching cMs and larger number of segments due to their algorithm which removes population specific segments.

The DNA adoption site has a relationship calculator that can help figure out closer relationships discussed in the article at Roberta’s blog called Demystifying Ancestry’s Relationship Predictions Inspires New Relationship Estimator Tool.

Autosomal DNA matching is not cut and dried due to the randomness of DNA inheritance and is even more confusing if you are from an endogamous population because your parents will likely share some DNA due to ancestral cousin marriages. Thus a match could be related on both sides! There is a function on the GEDmatch site that lets you check if the parents of a specific kit are related because they have passed along matching DNA segments.

I have sometimes found that someone predicted to be a 3rd/4th cousin based on total cMs is much more distant. This has happened when there are two good sized matching segments but each segment is from a different ancestral couple. Thus the relationship is much further back, for example, a double 6th cousin.

Another issue is the fact that the testing companies cannot tell which of the two paired chromosomes a match is on. So when you have a match that neither parent has, it is a false match created from small bits from each parent by the computer program (see my IBC article). This is why I prefer to look at matches that are “phased” that is to say a child and a parent have the same match.

If you only match someone on a single good sized segment (greater than 10 cM for most, more than 20 cM for the endogamous) your DNA relative can be anywhere from a 4th to a 14th cousin. See http://ongenetics.blogspot.com/2011/02/genetic-genealogy-and-single-segment.html?m=1 for a further discussion of that.

UPDATE 10/17/2017: There is now an easy to use online calculator based on Blaine Bettinger’s lastest chart at: https://dnapainter.com/tools/sharedcm that will show you all the possibilities for the shared cMs. Then you can use the ages of the testers plus test more relatives to try to figure it out.

Last but not least here is my data collection form which you can fill out right from this blog post (use the slider on the right to scroll down it to answer all questions).

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172 thoughts on “How to tell the relationship from the shared DNA

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  1. Thank you for this! 🙂 Especially with the half-sibling vs. grandparent to grandchild or aunt/uncle to nephew/niece relationship, which are all difficult to tell.

  2. In my project using 23andme comparisons there is a difference in segment counts for one relationship vs another.

    Grandparent-grandchild from 23 segments to 37 segments. The 37 segments is an outlier with 3 X-chromosome segments. Grandmothers appear to share a couple of more

    Ethan vs. Robert, 21.9%, 1629 cM, 23 seg (zero X-chromosome)
    Ethan vs. Janice, 25.4%, 1892 cM, 26 seg (zero X-chromosome)
    Ethan vs. Rocky, 22.0%, 1638 cM, 24 seg (79cM X-chromosome, 2 seg)
    Ethan vs. Vivian, 28.0%, 2082 cM, 37 seg (103cM X-chromosome, 3 seg)

    Kalea vs. Robert, 24.1%, 1792 cM, 25 seg (zero X-chromosome)
    Kalea vs. Janice, 25.7%, 1909 cM, 26 seg (full X-chromosome, 182cM)
    Kalea vs. Rocky, 28.1%, 2089 cM, 23 seg (full X-chromosome, 182cM)
    Kalea vs. Vivian, 21.9%, 1631 cM, 25 seg (zero X-chromosome)

    Shay vs. Robert, 21.8%, 1625 cM, 23 seg (zero X-chromosome)
    Shay vs. Janice, 28%, 2085 cM, 24 seg (full X-chromosome, 182cM)
    Shay vs. Rich, 19.7%, 1466 cM, 24 seg (full X-chromosome, 182cM)
    Shay vs. Marcy, 30.1%, 2236 cM, 29 seg (zero X-chromosome)

    1/2 sister vs. paternal 1/2 brother, 26.6%, 1978 cM, 32 seg (share no X)
    1/2 sister vs. paternal 1/2 sister, 29.2%, 2176 cM, 35 seg (share full X, 182cM, 2.45%)
    1/2 sister vs. paternal 1/2 sister, 23.0%, 1713 cM, 31 seg (share full X, 182cM, 2.45%)

    Paternal aunt vs. paternal nephew, 26.7%, 1984 cM, 46 seg
    Paternal aunt vs. paternal nephew, 26.2%, 1946 cM, 46 seg
    Paternal aunt vs. paternal nephew, 24.9%, 1850 cM, 42 seg
    Paternal uncle vs. paternal nephew, 21.7%, 1611 cM, 46 seg
    Paternal uncle vs. paternal niece, 25.0%, 1857 cM, 55 seg (includes 2X seg, 81.6cM)
    Paternal uncle vs. paternal niece, 24.5%, 1823 cM, 53 seg (includes 2X seg, 81.6cM)
    Maternal nephew vs me 20.1%, 1495.4 cM, 35 seg (includes 1X seg, 18.5cM)
    Maternal nephew vs my full sister 28.6%, 2127.8 cM, 40 seg (includes some completely identical X seg, 169cM)

    • I miss stated (completely identical X-segment), I was thinking about his mother and my sister sharing a large amount of completely identical X chromosome.

  3. Hi I saw your question posed on Facebook but wasn’t sure how to complete form properly so I’m happy to give you GedMatch numbers so you can take a look if you like

    Grandson (M4+1) A347430 and his Maternal Grandmother (M0) A903999
    Note Grandson’s paternal great grandmother is Ashkenazi/endogamic. Grandson is 8% European Jewish according to Ancestry.

    Nephew (M4+1) A347430 and his Aunt (M2) A219400
    Nephew’s paternal great grandmother is Aunt’s paternal grandmother. She was Jewish.

  4. Sorry I’m of no help, but I share 811 with a great uncle and 942 with a great aunt. When my mother gets her results in a few weeks, we will know how much is shared between her and her aunt.

    I did have a quick question. On 23andme, my great uncle got a little (0.1%) Sub-Saharan African. I was wondering if all the ancestors he has, I also have, but he doesn’t have all the ancestors that I have? And if he has African ancestry from a slave (as he has deep ancestry is from Kentucky and Virginia), would I also have that ancestor, just no Sub-Saharan African showed up for me on ancestry?

  5. The maternal or paternal question has now been added to the bottom of the form
    Please any of you who still have the window open so can edit their response, add that information. Anyone who cannot edi,t send me the answer with the total cM and aprox time and date when you added your numbers, thanks!

  6. Done – this was an interesting exercise. I provided information for me and my two brothers compared with my mother’s sister and my mother with my mother’s sister’s daughter.

    I also added my half brother, but that is from Ancestry.com (he hasn’t gotten around to doing more with his DNA – hopefully soon I’ll get him on GEDmatch).

  7. This is very timely as I am trying to figure out if my FIL has found an aunt or a half-sibling to his match. They match at 2009 cM with 45 matching segments, the largest being 199.3 cM’s. FIL was b. 1947 and the match was b. 1938, so this is probably not grandparent/grandchild relationship.

    We did not know of this family, I was looking for a different paternal family.

    The match has a nephew (a son of her sister) who matches at 1548 cM and 42 matching segments with the largest being 100 cM. The nephew was b. 1973. It is assumed that the nephew and the aunt are full matches, not half, but the nephews mom has not yet tested.

    The nephew matches my FIL with 747 cM’s and 26 matching segments, the largest being 77 cM’s.

    I am going to fill out the Google document for each. Thank you.

  8. Dear Kitty,
    Thank you for this helpful blog post. I recently uploaded my DNA to Gedmatch from Ancestry. I am adopted and know my birthmother. My half-sister will have her DNA results soon. However,I had an interesting match come up and using your Google form, it appears that the gentleman in question is either a half-sibling, Uncle, or Grandparent. I was surpised given that our shared cM’s are not that high- 59.8. Perhaps I filled out the form incorrectly. Thank you in advance for any thoughts on this matter.

  9. Hi Kitty. I have entered two grandparent/grandchild and six aunt/uncle to nephew/neice for you! Will be interested to see the outcome of this data analysis.

  10. I completed the form for my match with someone who we both grew up believing we were 1st cousins. Recent revelations have caused us to wonder if we might be half-siblings. Thank you for helping us.

  11. I took a DNA test in Ancestry . 1 girls on 50, one 52, and I’m 58 matched my DNA . They have 1600 and 1700 centrimorgans of mine. They were both adopted at birth. The one with 1700 centrimorgans said she found her birth mother before she died. She ask her who her father was and she said Dennis Williams, That’s was my dad. I knew then she must be my 1/2 sister. The other girl shares 1600 centrimorgans she was adopted at birth in Oklahoma City. We lived there too.
    They have 47 segments .
    How can I be sure they are my 1/2 sisters? I believe they are I can’t be their grandma, aunt , cousin etc,

    Thanks
    Cindy K

  12. Pingback: Relationship Estimates - Beneath the Cairn

  13. Hi Kitty,

    I’d done the Ancestry DNA as has my first cousin (maternal) and his father (my maternal uncle), but the “relationship” came up not as expected. My cousin matched with me at the level of 2nd cousin (293 centimorgans shared across 14 DNA segments) and my uncle matched at the level of 1st cousin (797 centimorgans shared across 35 DNA segments) which was my first hint that something was a bit off (on the other hand, a first cousin on my paternal line matched exactly as expected). So…I had my mom do the test. And she matched to her brother at the level of first cousin (1,761 centimorgans shared across 60 DNA segments). From my reading here, my assumption is that they are more likely to be half-siblings than full siblings (they are about 10 years apart). I’ve also read about looking for large segments of green on GEDmatch one to one compare and am hoping they will upload to GEDmatch so I can do so.

    My assumption is that they have different fathers vs. mothers as having different mom’s would mean my grandmother raised another woman’s child as her own…which I feel would be highly unlikely. But want to make sure I rule in and out every possibility before I present this info to my mom and uncle. My question is how I would be able to tell if they had different mothers vs. different fathers?

    • You are right that they almost surely have different fathers. If they both upload to GEDmatch.com, you could check their X, if they share a significant chunk or two then they have the same mother. However if they share no X, it is not a sure thing that they have different mothers, just about 98% or so (a guesstimate).
      Best is to compare each of them to their maternal and paternal side cousins to confirm which lines they match on. 2nd and even 3rd cousins will do for that.

  14. I have done the Ancestry DNA autosomal test a couple of years ago. I have noticed a trend of DNA shared with me of some of my cousins on strictly the paternal side and have compared the results with the DNA Detectives chart. The results have been for the most part, trending lower than the average cM shared as per the chart, going from my closest to the more distant known cousins..
    Examples: One cousin shares 975 cM across 42 segments which meets the charts average cM shared expectations – no argument there: A first cousin once removed shares 270 cM across 15 segments with me which is very low, compared to the average per the chart of 450 cM; a 2nd cousin shares 215 cM with me, which is below the average of 224 cM; A 3rd cousin shares only 14.1 cM across 2 segments and says I’m a 5th to 8th (distant) cousin which is absolutely not true and the average is supposed to be 56 cM; I also have a 3rd cousin once removed, who only shares 13.6 cM across 1 segment and says I’m a 5th to 8th cousin (distant) which is very low because 30 cM shared is supposed to be the average per the chart.
    It just seems like my paternal grandparents all the way back to my great-great grandparents (paternal) did not share much DNA down to me or my proven known cousins. Why??
    With this below average trend of shared DNA, is it possible that my 5th cousin and her Aunt would only share 4 to 5 cM with me, if I uploaded my DNA to Gedmatch? I would expect so. I did notice an online chart, similar to the DNA Detectives chart on that also.

    • Tony,
      DNA inheritance can be quite random after close family. I only got 22% from my maternal grandmother, rather than the expected 25%. As I discussed in the article one 2nd cousin shares twice as much with me as another but this did not hold true for my first cousins with those same 2nd cousins.
      After 3rd cousins it gets more and more random, so don’t read anything into it.
      However, do check of you have matches on all lines since another explanation for consistently sharing less is that they are all half cousins and there is an NPE up your paternal line.
      Finally, do be aware that ancestry removes pile up segments so their numbers can be lower.

  15. Is there any way to determine that this information from ancestry can definitely determine whither a person is a niece or a first or second cousin. From ancestry this person shares 418 cm across 22 segments. We know that she is my nephews child. When my grandmother was 41 and her oldest child(my mother ) was 13 she past of complications of uterine hemorrhage and my mother and her siblings we spit up in different states. My mother and my “sister” was the only ones kept together. Strangely my sister”s birthday is only days after her the date on her signed death certificate. We were wondering if my mom and sister are really siblings instead of mother and daughter. If they were said to be mother and daughter to keep them together. My grandfather ended up in prison about that time. My mother and her siblings are all dead. My sister was 27 years older that I am. My sister is my nephews mom.

    • Carolyn –
      This is a bit complicated of a story. Can you test your mother and your “sister”? If so, you uploading their results to GEDmatch then comparing them would tell us. But it sounds like you are trying to determine this from other tests?
      Your great-niece shares less than the normal amount of DNA for that relationship. But ancestry removes some matching segments so again, get those numbers fromGEDmatch. See this page for expected amount of shared DNA for different relationships
      https://isogg.org/wiki/Autosomal_DNA_statistics

  16. Me and my first cousin share 6.4 .But 23 and me says we are first cousins once removed.I beleave my grand father is my real father.And his mother is my half sister.I think thats why 6.4 not 12.Please help with all combinations.

    • Allen –
      I gather you mean percent? we usuall talk centimorgans (cMs) in genetic genealogy. You would share more DNA with your “cousin” if your father was his grandfather not less as you do. The amount you share suggests that you might be half first cousins (your related parents being only half siblings)

      See the chart here
      http://thegeneticgenealogist.com/2017/08/26/august-2017-update-to-the-shared-cm-project/

      I would recommend you test more cousins related via this family and make a mcGuire chart to see if you can figure out the relationship
      http://thegeneticgenealogist.com/2017/03/19/guest-post-the-mcguire-method-simplified-visual-dna-comparisons/

      • My sister took a DNA test and shows 31.% matches.But our heritage is different.I have Native American, Jewish, and she does not have them plus her % of others are very different.She has German I don’t.Could we be half-siblings or full?We do share English just about 30% difference between us.

        • Allen –
          Ancetry composition determination is far from accurate yet but shared DNA is very accurate.
          However it sounds like you might be half siblings since you are so far from 50% shared (total cM = ?).
          Unless you tested at 23andme, you need to upload to GEDmatch to see if you have a significant amount of fully identical regions of DNA (FIRs). See
          http://blog.kittycooper.com/2016/04/full-versus-half-sibling-dna-matches/
          for how to figure that out

          • Thank You! This answers how being the only son and treated so badly.My father never did anything with me like other fathers.He loved my sisters and I never felt that from him.At 15 he told me it was time for me to quit school and get a real job to start paying him back for the years of food and for putting a roof over my head.I got a job and stayed in school given him my paychecks.Now I can understand why he is mean to me.

      • mskitty: Could it be that it could be my uncle could be my father instead of my dad?I’m just trying to understand who I am.My sister took DNA test also (2387.cm)32% largest 187.cm.My first cousin, I described to you on 8-29-17 as 6.4% and 16 overlapping segments.My sister and my cousin ancestry are very similar.Mine includes Native American, Jewish, a little more of African and I show on the low end of Neanderthals with no German.They show German, and more English than me.

        • Again, you cannot rely on ancestry composition for relationship testing. It is not good enough yet.
          Always look at the actual centimorgans shared. You have the same father as your sister and your cousin had the expected amount shared for a cousin

  17. I’m a newbie, if this is the wrong spot to ask a general dna question, I apologize. I share 1153 cM over 36 segments with someone (Ancestry DNA test).
    How much DNA might we share if this person were the daughter of my half-brother and a woman who is not my mother? Or, the daughter of my half-brother’s son and a woman who is not my mother?
    I feel inadequate at this and I just bought you a glass of wine to thank you for answering such questions.

  18. I am a bit confused. There has always been a question as to my birth father. My father questioned my paternity and my mom denied any problems. I hope that my niece who is a match on ancestry dna at 1347 cM at 52 segments is my full niece . I would appreciate your thoughts as we only share 19% of our dna.

    Ps
    It also appears that some of my shared matches, match both my father’s mother side with my mom’s side.

    Thank you for your help and wonderful blog.

  19. Hello,
    A group of my family members (father, my 1/2 sister and her 2 kids, my aunt and her daughter) have done 23 & me. I looked at different pairs of relationships -total shared cm’s & # of segments to try and determine if the numbers seemed to make sense based on the closeness of the relationship. I don’t think they do make sense.

    My first question relates to my father and aunt. When I compare their data they share a number of complete cm’s, and a number of 1/2 identical cm’s. Is the total number of cm’s they share the sum of these 2?

    My second question, would my Dad and his grandson share any complete dna?

    My Dad was born 1st and my Aunt followed. I am wondering if my father’s father, is actually the man he believed to be his grandfather.

    Any feedback you could offer would be very much appreciated.

    Thank you

  20. Hi Jane –
    Make yourself a McGuire chart to look at the relationships. I find this most useful for clarifying them
    http://thegeneticgenealogist.com/2017/03/19/guest-post-the-mcguire-method-simplified-visual-dna-comparisons/

    To question 1: Normally just the half identical segment total is used. However 23andme shows you both totals in the comparison found at 23andme tools > DNA relatives > DNA. Warning, it includes the X and all segments > 5cM so some adjustments are needed to use this with the various charts.

    To question 2: Your Dad and grandson would normally not share any significantly sized fully identical segments unless his Dad is closely related to you.

  21. Thanks again, I will try to do that, but not sure how to find the paternal side.

    Do the number of generations make a difference? Gedmatch says we are separated by 1.7 generations.

    • Gosh, I thought I had a handle on my understanding, but I seem to have confused myself. I do have a cousin match with no x match and we match at 144 cm with the largest at 47 and my niece matches that one with 84.9 with 35.7 at 3.7 generations.

      I think it is from the paternal line, but I have really confused myself. I intend to study this gedmatch info and try to figure it out.

      I can not thank you enough and will continue to follow your blog.

  22. Hi Kitty,

    Here is the info:

    Aunt & Dad
    Half Identical 2858 cM – 44 segments
    Completely Identical 1015 cM – 37 segments

    The possibility I had in mind is
    Aunts Mother = Sally, Aunts Father= Hank
    Dads Mother = Sally, Dads Father = Hanks Father

    Additional relatives who I have 23 & Me data for include:
    Aunts daughter
    My 1/2 sister (share Dad in common)
    My 1/2 sisters daughter & son

    Initially 23 & Me identified my niece as my grand daughter.
    My nephew shares a great deal of both half identical
    And complelty identical DNA with my father (his grandfather)

    Thanks so much for your reply

  23. Hi Kitty,

    Apologies- I didn’t see your reply to my 1st post before adding the 2nd.

    Your answer to my first post took my back to 23 & Me to look at the DNA shared between my father and my 1/2sisters son. the identical DNA shared between them is on X.

    The overall breakdown on their shared DNA is as follows:

    Half Identical 1481 cM – 27 segments
    Identical 53 cM – 2 segments

    When I read your reply about the unlikelihood that they would share any identical DNA I thought that maybe this would be the smoking gun lending possibility to my fathers real father being the man he knew to be his grandfather…. then, I saw the post about x, and uncombined… and I see that maybe it’s not that simple. Any thoughts?

    • A man has only one X otherwise he would be a girl so his X matches are always fully identical, thus that is not meaningful

      As to your puzzle, I am not sure why you think the grandad might be the Dad, those numbers look like normal full siblings to me.

      You could test more cousins related to the grandad

      • Hi Kitty,

        Thanks for the feedback. I created a McGuire Chart plugging in the numbers and was wondering if there is any way I could email it to you? The one hazy area is whether or not the total percent shared for full siblings (via 23 & Me data) is solely the 1/2 identical figure, or, the 1/2 & completely identical added together. I had sent you 2 vinos the other day- hopefully those went thru. 2 more on the way.
        Grateful for your generosity in sharing your knowledge!

  24. Gosh, I thought I had a handle on my understanding, but I seem to have confused myself. I do have a cousin match with no x match and we match at 144 cm with the largest at 47 and my niece matches that one with 84.9 with 35.7 at 3.7 generations.

    I think it is from the paternal line, but I have really confused myself. I intend to study this gedmatch info and try to figure it out.

    I can not thank you enough and will continue to follow your blog.

  25. Ms kitty, have all my questions, I bought you a glass of wine.

    Still trudging forward, but getting cross eyed with numbers.

  26. Hi,

    I have found a cousin on 23andme and our family trees are not connected. My cousin heard rumors that his father’s mother was actually his sister. So Jane and John were raised as siblings, but Jane may have actually been John’s mom. There was no mention of who John’s father could have been. My cousin, James (all names changed), is John’s son.

    Some of my family lived in the same town where Jane was located when she, supposedly, became pregnant with with John. My grandfather and great uncles were near the age of Jane when she got pregnant, 18.

    I ran our 23andme data through the relationship estimator and we are estimated to be 1C1R [11111] or 1C [10110]. My daughter and some cousins on the paternal grandmother side have taken the 23andme test. My mother will be taking the test and another cousin on my paternal grandfather side will take the test too.

    Jame’s DNA Match to me
    Based on Seg of 5 cM or greater
    Total cM 567
    Longest Segment cM 48.2
    # of Segments 21
    % Shared 7.660

    With all the data we have and will have, where can we go to better narrow down the potential relationship possibilities?

    Thank you in advance!

    • One problem with Family Tree DNA is that they include segments smaller than 7cM. After you toss out those smaller segments, if you are still matching for about 500cM then still likely in the first/second cousin range

      Sounds like you are doing the right thing, getting as many family members to test as possible to sort this out. Most important is your mother. Does she have any brothers? If she does not match then it is on your dad’s side.

      Another possibility is for James to get his Y DNA tested which may provide a surname …

  27. I got my results from 23andMe with 1090 cMs, 20 segments, 14.6% shared and says we’re 1st cousins, is that even possible? We are definitely half relatives, if that helps.0

  28. Hi, I could not complete all questions, and I’m not positive of my parents being my actual parents, but my one and only match was with someone I did not know and about 20 yrs younger. Ancestry DNA had put us as 1st cousins at 663 cm & 37 markers? She too is not at all positive of her birth parents. Could she possibly be a half sibling or a half Aunt? Thank you

  29. Thank you so much Kitty! I’m only 2 days new to this and I have read how it works but is so confusing to me, especially having no other DNA with anyone to go by & when I put 35markers, was supposed to be 32. I’m sorry to have had bothered you with this, but I’m just lost…. 🙂
    Thanks so much!

    • Shannon
      Patience … Give yourself some time. Keep reading and looking at your results, it will start to make sense eventually

  30. Hello Miss Kitty,
    More wine coming your way. I’m female and match an unknown man on Ancestry. I’ll call him D.
    •D matches his known half-sister at 1377 (they have the same mother).
    •D matches his own granddaughter at less than 1300.
    •D matches me at 1373 cMs across 44 segments.
    •D’s son matches me at 961 cMs across 25 segments.
    •Ancestry has defined D and me as Close Family –and D’s son and me as 1st Cousin.
    * In the Close Family category, I know D is not a great grandparent or Uncle, nor is he a child of my full sibling.
    * At 1373 cMs, I believe D could possibly be a half-brother or half-nephew.
    * If D is my half-brother, his son is perfect for half-nephew at 961.
    * But if D himself is my half-nephew, then his son’s number is very high for a great half-nephew. What do you think? Thank you so much.

    • Wanda, it sounds like you have answered your own question and eliminated the other possibilities. He is your half brother. It would be good to get him to upload to GEDmatch and I would happily look at the comparison there for the two of you.

  31. Hi Kitty can I call upon your expertise.
    I have a match on ancestory as a 1st cousin, we share 804cms (gedmatch)
    i share 373 cms with his daughter
    he was adopted and only info was that his bio father was a young (my name)
    I have no idea who my fathers father was as he was brought up by his grandmother (young)
    at 1st the result looked as though I am a half Nephew but there is a 3rd person who he has a match with as do I on ancestory who is a relation of my grandmother (young nee bushnel) he comes up as 3rd or 4th cousin
    he hasnt uploaded to gedmatch

    any thoughts?

  32. Kevin –
    That is really not enough information. What are your relative ages? So the issue is that if he is a Young why does he have this 3rd/4th cousin match with your grandmother? Sounds like he is related to your Dad who would have both lines. Did your Dad or you have any brothers?
    Get as many known relatives of yours to test as are willing to help with this mystery.

  33. Sorry Kitty I didnt put it very well.
    I am 62 he is 70
    the 3rd/4th cousin is the relation to me to the 3rd person who is a descendant of my great grandparents.
    my dad has a couple of living cousins as do I so i will see if they can get tested

    Thanks

  34. Basically want to tell what relation he is to me
    this is the gedmatch result

    Chr Start Location End Location Centimorgans (cM) SNPs
    1 238,254,256 240,773,066 7.6 716
    2 77,916,406 133,326,827 42.8 5,861
    2 202,658,096 235,840,151 48.0 5,526
    2 236,089,121 242,565,979 13.4 1,207
    3 120,836,583 151,154,829 32.1 4,311
    3 157,730,821 187,609,004 30.2 3,766
    4 6,829,453 10,337,857 9.8 824
    4 84,460,381 92,046,301 8.4 1,025
    6 6,171,146 21,798,151 27.8 3,191
    6 124,399,036 138,863,401 18.4 2,268
    7 7,972,287 26,162,119 27.7 4,051
    7 145,948,007 152,927,182 15.4 1,356
    8 37,288,402 72,408,012 27.0 3,726
    8 74,856,303 115,097,126 29.3 4,700
    8 139,853,147 146,241,933 10.7 1,143
    11 22,308,958 108,678,237 71.1 11,209
    12 93,073,105 126,075,474 47.1 5,852
    14 52,679,619 99,760,931 64.1 8,221
    15 20,614,243 37,027,402 37.9 3,141
    15 67,910,978 77,127,099 8.4 1,168
    15 93,491,713 98,574,626 14.8 1,241
    16 7,400,811 10,252,326 7.4 849
    16 12,199,639 22,744,262 16.8 1,577
    17 10,164,422 58,988,240 63.1 6,979
    18 102,535 2,881,478 8.4 662
    19 489,994 38,923,549 56.7 4,535
    19 40,112,681 57,932,919 32.2 2,941
    20 7,448,401 13,190,328 13.4 1,290
    22 37,959,275 43,840,446 8.6 1,007
    Largest segment = 71.1 cM
    Total of segments > 7 cM = 798.7 cM
    29 matching segments
    Estimated number of generations to MRCA = 2.1

    435222 SNPs used for this comparison.

    • The data is a very good fit for half uncle. There are other possibilities based on cMs and ages (1st cousin, half first cousin) but the low number of segments suggests a close relationship.
      How large is the match to your grandmother’s line by this 3rd person? Unless his match to you and to the adoptee triangulates these could be from different unrelated lines. For example this 3rd person could be related to your grandmother on one line and to the adoptee on a totally different line.
      Get a few more cousins to test, a cousin on each grandparent’s line and perhaps each great grandparent line also … the more the better!

      Also if you are interested in figuring out who your father’s father was, go to DNAadoption.com and take some classes or just read their materials.

  35. Fantastic post Kitty. Thank you. I have my own situation I was hoping to run past you:

    I have a match on AncestryDNA that is 793 centimorgans shared across 32 DNA segments. Ancestry thinks that this is my first cousin.

    I can identify this person as being from my mother’s father’s side due to ethnicity. My mother was adopted and she never knew her birth parents. It is almost certain that her birth parents never had another child after her.

    Accordingly, I am almost certain that this person cannot be my first cousin.

    I believe this person is my mother’s half-sibling, i.e. my half-uncle. Do you think this is correct? The only other relationship I think could be possible would be first cousin once removed (i.e. my mother’s father’s sibling’s child, i.e. my mother’s cousin). However I looked at the histograms for the latest SharedCM project (August 2017) and this would put us in the 99th percentile for amount of DNA shared, which seems very unlikely.

    Can you tell me if my analysis is correct or if I’m missing anything? I am also a little vague as to the significance of / context for our centimorgans being shared across 32 segments.

    I would be so grateful for any light you can shed on this!

  36. A mother, her brother, her son, her daughter compared to a non-related Male and his Half brother.
    Only the Daughter’s Autosomal test matches the non-related Male. 48.5cm Total and 48.5 largest.
    Is the Daughter alone, apparently related to the otherwise non-related Male from her Mother’s side?
    The individuals do not share matching mtDNA haplogrouping.

    • The daughter would be related to the unrelated male on her father’s side since her mother does not have this match. I removed the kit numbers, we never publish these for privacy but I will take a quick look and email you.

  37. I uploaded my raw DNA to GED MATCH. Not sure why because i have no idea what all this means. are there people you can hire to look at these results . says i have 90 matches. i have like 3 that are highlighted in green. Ughhhhhh ,
    any help would be appreciated.

  38. I have a question about full vs. half siblings. I am an adoptee that has found my bio mom and siblings. My brother and mom both tested at Ancestry and I uploaded both to Gedmatch. My son tested at 23andme and I uploaded to Gedmatch.
    As far as I can tell my brother and I are full siblings. Our mom is from the San Luis Valley. The gedmatch test for “are your parents related read”:

    Mother 4.6
    Brother 2.5
    Sister(me) 2.8
    My son parents not related.

    Our numbers on Ancestry are:
    Brother to sister 2,515 65 seg
    Brother to mom 3,478 49 seg
    Sister to mom 3,458 62 seg

    Our numbers on Gedmatch are:
    Brother to sister 2635.5 145.9 on X. Gen 1.2
    Brother to mom 3586.2. 196.1 on X. Gen 1.0
    Sister to mom 3586.1. 196.1 on X. Gen 1.0
    My son to brother 1815.6 145.9 on X. Gen 1.5
    My son to My mom 2158.8. 174.1 on X. Gen 1.4

  39. Suzanne-
    All those numbers look pretty normal but I am not understanding the “are your parents related?” result – are those generations (gen) or cMs? Does your mother know who your father is? And who her parents are? I will email you

    • Hi Kitty,

      The “are your parents related” result on Gedmatch is given in MRCA form: most recent common ancestor. My mother is 91 and has dementia so I don’t know if she would be able to tell me.

      Thankyou for any guidance you can provide.

      Suzanne

  40. My closest match is the data below. Can someone tell me if this person would be related and if so approximately the degree of relation? Thank you.
    Total CM: 26.6
    Largest CM: 10.1

  41. Literally at my wits end trying to help family only to realize I’m the one who needs help in order to provide them help…if that makes any sense?
    My cousin, lets call him “A”, contacted me out of the blue because I’m the “family tree guy” in the family. He told me he’d done the AncestryDNA test & the 23/me DNA test and that he was contacted by a woman on 23/me, let’s call her “B”, she’s about 69 years old, and she was trying to figure out their connection because she was adopted out at the age of 6 weeks in 1949. My cousin, A, also in his late 60’s, was her highest match and she his on 23/me indicating a 2nd cousin match. He asked if I could help figure out their relationship in hopes of discovering her birth parents names. I don’t use 23/me, don’t really know much about it, but I am on GEDMatch so I got and uploaded their rawdata to see if B was also related to me (male-age 49). She was not. Since my cousin and I match through his dad’s parents (his gm is a sister of my ggm) I figured she must match him on his mothers side. I checked for a match at X and they have shared X DNA. I then tested one-to-many matches to see if they shared any other close matches. They did. Just one. A male, age 49, let’s call him “C”. Note; C has no X DNA shared with either A or B. He also was not a match to me.
    Anyway, I reached out to C for information only to be shocked by his answer that he had little info to share because he too was placed for adoption, but 20 years later than B, in the year of his birth 1968. He did have a letter from the adoption agency which provided him with his parents basic background, the mother’s physical description and most importantly her birth date.
    He did have an Ancestry DNA test which both he and my cousin A matched on and both also assigned me as the manager of their DNA tests so I could try and figure out who C’s birth parents were. B was also invited to take the AncestryDNA test (we are still awaiting the results). So cousin A & C had about 6 shared matches at 3rd/4th cousin, but C also had two 1st cousin matches that were unrelated to my cousin A. I contacted the closer matches and learned who C’s birth mother is using their info & their trees and his mom’s birth date. Through that connection I put him in touch with his new found siblings, some of whom are now doing the AncestryDNA to confirm C’s relation to them, before they broach the obviously sensitive subject with their mom. The agency letter made it absolutely clear that C’s father was not the father of these siblings. My search for C’s dad continued using the other shared matches at Ancestry with cousin A, since now we knew which matches were to C’s mom and that which remained as shared matches with my cousin A must be for C’s dad.
    Using those matches and researching the last two weeks I’ve finally discovered last night just how cousin A relates to these other matches. A’s great grandmother, on his maternal side, had 5 siblings; let’s call this whole bunch “Group D”. Each of the remaining shared matches on Ancestry between A & C lead back to Group D.
    Remember though, A, B & C all relate to each other at a 2nd to 4th cousin level, but only A & B have the shared X.
    Group D collectively, all born between 1870 and 1884, went on to produce over a dozen children of their own, collectively their issue begat children numbered in scores, and now I’m looking for a young male in his early 20’s in mid 1967 out of a group of just over 130 souls. Many of whom, despite weeding out those who are not male and not in their low 20’s in 1967, still leaves a sizable pool near 40 individuals and I’ve not found them all yet either.

    Questions I’m struggling with:
    Since A & B share X DNA and C does not, yet all are related, what’s the best way to learn who B’s biological parents are?

    Since B is related to A at the 2nd cousin level (higher than I am related to A) where should I look in my tree for her parents, before A’s grand parents birth or after?

    C’s dad…with such a huge field of candidates to sort through to determine who he is, is there a shortcut you could recommend?
    Here’s how all our DNA stacks up if it helps:

    My match to cousin A on GEDMatch is summed up as:
    Largest segment = 48.5 cM
    Total of segments > 7 cM = 159.1 cM
    8 matching segments
    Estimated number of generations to MRCA = 3.2
    No X DNA

    B’s match to A is summed up as:
    Largest segment = 54.9 cM
    Total of segments > 7 cM = 302.1 cM
    12 matching segments
    Estimated number of generations to MRCA = 2.8
    X DNA = 47 cM

    C’s match to A is summed up as:
    Largest segment = 28.4 cM
    Total of segments > 7 cM = 130.6 cM
    8 matching segments
    Estimated number of generations to MRCA = 3.4
    No X DNA

    C’s match to B is summed up as:
    Largest segment = 35.1 cM
    Total of segments > 7 cM = 147.2 cM
    6 matching segments
    Estimated number of generations to MRCA = 3.3
    No X DNA

  42. Boy are they lucky to have you on the case!

    The shortcut is to use GWorks, see http://blog.kittycooper.com/2017/09/solving-unknown-parentage-cases-with-dna/
    After running GWorks, I look at the spouses’ surnames for each child and follow that line when the surname has some frequency.

    The older version of the DNAgedcom client also has a tool called match-o-matic which you can use to compare 2 match lists (the m_ files) for matches in common or different.

    By the way, I use this calculator to better determine the likely relationships (thus where to look on my tree)
    https://dnapainter.com/tools/sharedcmv4

    Having no X is meaningless except for close family relationships.

    Last but not least, check out the resources at DNAadoption.com

  43. Good afternoon. I received results today showing that my boys share 2425 cm. It also put them in the Full sibling, half sibling, grandparent category, which still leaves my question unanswered . I know it puts them on the high end for half sibs but on the low end for full sibs. I live in a country with a population of less than 400,000 and it is likely that most of us are related in some way. How can I get further clarity on this?

  44. Hello,
    I am a newbie to this. I did the DNA through Ancestry (xmas present) in hopes that I would find a half brother that I have heard I had. In doing so, my closet match came back at 2147 Centimorgans across 55 DNA segments. Her son came back at 1136 CM’s across 34 DNA segments. Her birth certificate shows different father but she was adopted. I have learned this from her son. I would assume from everything I read that she would be my half sister and her son would be by half nephew. I uploaded my results to GED match. I know its not from my mothers side and we don’t share the same matches from her side. Can you let me know what you think?

    Sincerely,
    MM

  45. Thanks for your reply. She was born in 45 and myself in 58. So 13 years. I asked if she uploaded. I just uploaded mine today. I will compare once I know. But just so I understand if she is my half sister, then the blue line will be there fully for the X , correct?

  46. I submitted a DNA test to Ancestry, more out of curiosity as to my heritage than to find anyone. But what I have come back with is VERY interesting. Bit of back story, my dad left before I was born, I did not find/meet him until I was 20. We lost contact soon after, and because of this, I do NOT know him or his side of the family well (his mother has gone so far as to hang up on me and refuse to acknowledge I exist.) So, not people I can call up to ask for clarification.

    But the DNA test came back giving me hits to people being close potential relatives, that well….with some digging, I am highly curious to know the actual relation to. My mom recalled my father’s mothers name, and her husband. Well, in the tangled mess of trees’DNA, I discovered that (I hope I can explain this properly):

    I share CLOSE DNA with a Lewman/Goodwin side of the tree, but on paper that would be impossible. Since my father’s mother is listed as her maiden name being Snapp, born in 1932. Her mother did not marry one Mr. George Lewman, until 1949. But, share DNA with a woman who links back to George’s maternal Uncle, and a man who links back to George’s BROTHER.

    I have also recently had confirmed (I vaguely recall my father mentioning it when I met him), that he WAS adopted by his mother’s husband. So, I always figured my father, born in 1951, was a product of her and someone else, then she married her now husband (last name Rasch), whom she had two other kids with in later years. BUT, I have uncovered an older brother, born in 1948, who’s father is listed as her husband, Mr. Rasch. So???? Did she have two kids prior to marrying him, that he adopted, or did she cheat?

    Or, as I am thinking, was the man her mother married in 1949, Mr. Lewman (who years earlier was married to her inferred father’s cousin, on the Snapp side. Tangled web, I tell ya!) REALLY her REAL father? Or was he possibly my father’s father? I am trying to figure this out, with no way of actually asking anyone for answers. I contacted the people who’s DNA link I shared, asking if they knew any info, and they never got back with me.

    So, here is the breakdown, on the Goodwin side, my DNA match shares: 229.2 centimorgans across 11 DNA segments.

    On the Lewman side, my DNA match shares: 75 centimorgans across 1 DNA segement.

    And I did find some Snapp DNA with someone who is listed as a possible 5th-6th cousin, sharing 34 centimorgans across 2 segments.

    So, I am hoping you can tell me who I am actually closest to, I am assuming the Goodwin line. Just HOW close, they said 2nd cousin. And just how I can find out who might be the father of my father…I don’t know? I just wanted to see if I could get some clarification, lol.

    Thank You.

  47. Ok my husband does not know who his father was. He completed Ancestry DNA and has a “Close family- 1st cousin” match come back at 1450cM at 49 segments. Do you think this is more of a half-brother, half- nephew or 1st cousin? The tree this person has listed we cannot find any matching surnames in the DNA matches trees from other individuals. Do you think maybe this person is wrong on who their father was? Or is it common to not find the surname of who he is eventually. I just cannot make a match between any of the trees on the 3rd cousin matches. Thank you!

  48. I cannot tell from the cMs alone but the likely relationships is one of the 25% ones, so uncle/nephew grandad or half brother. How many segments?

    https://blog.kittycooper.com/2017/09/the-25-relationship-a-first-look-at-the-data/

    Save a copy of the match’s tree (pedigree thief or take a text copy via http://blog.kittycooper.com/2017/05/getting-a-simple-text-pedigree-from-ancestry-com/ )

    And then get in touch, carefully since it is probably a half brother see
    http://dnaadoption.com/index.php?page=email-to-close-match

    and yes he could be wrong about who his dad is. Have you used the GWorks technique to build down to your husband’s likely grandparents?
    http://blog.kittycooper.com/2017/09/solving-unknown-parentage-cases-with-dna/

    Have your husband upload to GEDmatch in case his match is there. You can tell from the segment sizes which relationship is most likely.

    good luck!
    Kitty

  49. Hi Kitty,
    What does a white perpendicular line between 2 segments in the 2-D chromosome matching chart. Its referred to as an “old match”
    Many thanks,
    Jo Treston

  50. Hi Kitty, my mother had relations with two brothers and I’m not sure which is my father. I found a daughter from one of them and she agreed to take 23andMe with me. She came back at 19.5%, 1449 cM across 37 segments. How conclusive is this to say what relation she is to me?

    Andrew

      • Thank you Kitty. If I was tested on 23AndMe v4 chip and she was tested on v5, should I anticipate the % shared, segment length, total cM, or number of segments to change?

        Andrew

  51. Kitty you once helped me above with the A,B,C group…but now a new mystery has begun.
    First an update: We still cannot find the missing link between A, B & C but we’re okay with that for the time being, we are on the right path and we’re sure an answer is coming soon. C is in touch with his bio family and I’ve reunited B with her bio family and everyone’s talking in private chatrooms on facebook. So that worked out, however…poor B. Even though I found her bio mom’s family and put her in touch with half siblings on that side, the family on her dad’s side, has been harder to figure out.

    So far we’ve only determined the family she came from which consists of 5 siblings (4 males/1 female). My thought is that one of the 4 is most likely her dad and if not then the father of the 5 is. I’m in touch with the children of the 5, all of whom are over the age of 42 and they’ve all been a great help! So far two of them, both female, have taken AncestryDNA tests (one belongs to the child of the female, the other is the child of one of the males. They both match B at what seems to be 1st cousin. And here is where I get lost in the weeds:

    The two known cousins, let’s call them D (child of a male) & E (child of the female), on Ancestry, match each other at ‘1st cousin’. When I run the comparison at gedmatch I get these numbers:

    D & E: Largest segment = 68.5 cM
    Total of segments > 7 cM = 824.3 cM
    27 matching segments
    Estimated number of generations to MRCA = 2.1

    D also has an X match with E:
    Largest segment = 77.0 cM
    Total of segments > 7 cM = 87.2 cM Actual.

    When I run B & D:
    B & D: Largest segment = 123.0 cM
    Total of segments > 7 cM = 1,192.1 cM
    34 matching segments
    Estimated number of generations to MRCA = 1.8
    D also has an X match with B:
    Largest segment = 42.0 cM
    Total of segments > 7 cM = 79.4 cM Actual.

    When I run E & B:
    E & B: Largest segment = 77.2 cM
    Total of segments > 7 cM = 816.5 cM
    35 matching segments
    Estimated number of generations to MRCA = 2.1
    There is no X match between E & B

    So the questions I have are:
    1. Why is it that there is no X match between E & B when there are X matches with D & E and D & B if all are 1st cousins?

    2. Is there a good reason why B and D tested out as a higher match than E & D and E & B? 1192cM vs 824cM and 816cM respectively

    3. If in fact B’s father turned out to be the grandfather D & E, that would make B a half-aunt of D & E, do any of the result I’ve displayed here so far rule that scenario out as a possibility?

    4. Do these results indicate anything to you that I might be overlooking?

    Thanks a bunch

    • To answer
      1. Why is it that there is no X match between E & B when there are X matches with D & E and D & B if all are 1st cousins?

      Random. Do not worry about the lack of an X match, ever. This only eliminates sisters with the same father who must share the full X. I have even heard of rare cases of full siblings (2 boys) with no matching X.

      2. Is there a good reason why B and D tested out as a higher match than E & D and E & B? 1192cM vs 824cM and 816cM respectively

      No, DNA gets more and more random after very close family. Note that males will do less recombining of there DNA so it is normal for the child of a male to share larger segments with B. Both totals are solidly in the first cousin range, use this calculator
      https://dnapainter.com/tools/sharedcmv4

      3. If in fact B’s father turned out to be the grandfather D & E, that would make B a half-aunt of D & E, do any of the result I’ve displayed here so far rule that scenario out as a possibility?

      That possibility is not ruled out at all. To rule it out you would need good autosomal matches to the grandfather’s wife. If there are none, try target testing a descendant of one or more of her siblings. If no match then yes it is the grandad.
      If you can test a child of every son that would be best of course.

      4. Do these results indicate anything to you that I might be overlooking?
      Use the are your parents related on B to be sure they are not
      and see the ansewer to 3

  52. I just scrolled up and saw a reply you left for Andrew and at the end you left this line that caught my eye:
    “If (you) have at least 2 shared segments greater than 100cM then for sure she is your half sister”

    Is that a universal application or more specific to Andrew’s situation and the 1400+cM he and his half sister have?

    In my example above, where D matches with B with what Ancestry interpreted as a 1st cousin match, when I ran the dna for both on gedmatch using the 1 to 1 comparison, the reading was 1192cM and they DO have 2 segments over 100 cM. 123 and 115 respectively. I originally dismissed the idea of them being half sisters based on what I gleaned from another of your blog posts where you indicated ‘if two half sisters have the same father they would have a full blue bar on the bottom in an X chromosome 1 to 1 comparison on gedmatch’; Now I’m wondering if I misinterpreted that?

    Thanks again!

    • If they shared a father then they have to share a full X.

      Having 2 segments over 100 is a guideline to use when the total DNA is either a half sib or a aunt/niece relationship. See https://blog.kittycooper.com/2017/09/the-25-relationship-a-first-look-at-the-data/

      Yes D and B could be half sibs with a shared mother by the numbers but you are looking for the father, not the mother, right?

      It is very unusual for first cousins to share more than one segment > 100 and I have not seen this before. Is this population group at all endogamous?

      Now to answer your other questions.

    • Thank you for the replies! Combining my own replies to this single post:
      Yes, we are looking for B’s father. No, B’s parents are not related. Yes, I ran the DNA painter, but my post was so long already I didn’t want to add those results too. This is definitely not an endogamous population group.
      We are only able to DNA test a child from 3 of the 4 males; we are awaiting the last two test results now.

      Regarding the 4th male we only have access to 2 granddaughters, both are willing to take the test if needed, but I’m not sure what good their testing would do, since at best B would only test as a half aunt, at worst a grand aunt, to the pair?

      If neither of the 2 pending results is a conclusive half-sib match, we’ll then wait for the results of the granddaughters of male #4 at which time expect yet another glass of wine since I know I’ll need help sorting that out too. 🙂

      On the gedmatch ‘1 to many test’ I noticed that D, who is B’s top match, shows a total cM count of 1210, slightly higher than the ‘1 to 1 test’ at 1192; when using DNA Painter in such an instance should we use the 1 to 1 result or the 1 to many result or does it not even matter?

      Also, you mentioned you have never seen two >100 cM segments in a 1st cousin match, I’d be happy to privately share the kit numbers with you if you’d like to review the results directly. Email me and let me know.
      Thanks again!

  53. Yes test those grand daughters. The more tests, the easier to sort it out. Draw a McGuire diagram …. I will email you

  54. I find a match (MyHeritage) of 36.2 cM (on 2 segments, one on chromosomes 13 and one on 15, the largest segment size is 21.2 cM) with another who I suspect is an 8th cousin who is English. My American family descended from an English immigrant to the US in 1749. We suspect we have a common 8-9th English ancestor. Our American side has had no further contact with the English side as my “potential” eighth cousin’s family remained in England. Are the chances good that we have verified the family connection?

    • Thomas –
      No the chances are not all that good. I mark a match like this as a maybe. Back that far there can be other connections that neither of you is aware of.
      But then again, it could be. Perhaps you should both upload to GEDmatch, buy the tier 1 for a month, and use their triangulation function to see who else matches you two on those segments and whether they have similar ancestry ….

  55. Here’s what my mom shared with me.

    Mom and Dad were married 60 years
    Mom/Dad had one son together, J
    Mom had second son P; P had a different bio father (2nd man)
    Mom had daughter (Me). I had a different dad (3rd man)

    P & Me did 23&me. We share 30.8% of our DNA
    23&me says P is my uncle (since there were only 3 of us, that means J’s daughter. )
    Given that we most likely have the same mother but different fathers could we be 1/2 siblings?
    Or could my parents be mom and J?

    Mom/Dad/J are all deceased so we can’t do DNA.

    Thanks.

  56. Can somebody please help me. I got a new match a few months ago. Shows as 1st. My family on Dad’s side 1st 2nd 3rd cousins aunts uncles all did their DNA. This man and I only share my kids as matches. So I am assuming his is from mom’s side as none of them have done their DNA. This is my question . We share 1046 centimorgans over 34 DNA segments. He was conceived in Kenya in 1952. Does this mean he is the son of one of my uncles from my mom’s side that was in kenya in the military. Someone please help. I don’t understand these charts

  57. I am totally new this DNA arena and need help. I just got my Ancestry DNA results back over a week ago. I have 3 close family matches. One I know is my mother’s sister with whom I share 1,645 cM across 80 DNA segments. Then there are two females that I have no idea who they are so I reached out and one replied back. She informed that the other match was her twin sister with whom I share 1,850 cM across 71 DNA segments. I share 1,569 cM across 65 DNA segments with her. ( I hope I didn’t confuse you)

    This would put them as possible half-siblings or aunt? They are 40 and I am 46 so I can’t see how they would be my aunt but then again anything is possible. I know my father has other children by other women. My match and I are baffled by this. My mother’s sister is not a match to these twins. My mother has agreed to take a DNA test but in the meantime, I am left confused.

  58. In the case of a half-sibling test,me,being male and Suzy being female sharing same father,showed 15.6 % relatedness.Would the Y chromosome be less prevalent in the female offspring?Is this percentage enough to seal the deal? Thanks

  59. Sorry Edward, my expertise is with personal genome tests like 23amd me or ancestry or … Those tests sample many many more data points than a simple relatedness test…

  60. I am so over my head with this DNA information. I had my DNA done on Ancestry in October 2016 and posted it on FTDNA & Heritage. No surprises in my DNA, 6 of my 8 great grandparents were born in Ireland, other 2 were from England. My results are also on Gedmatch which has been fun. I have a lot of numbers and am not sure which ones are the most important. I have 7 Gedmatch one-to-one comparisons in front of me. We all match on Chr 2, the cM go from 14.0 to 33.0 and all the locations are within the same range … 56,356,533 to 98,116,322. I have looked as several of their trees to no avail. Where do I go from here?

    • Sharon,
      If that is the only segment where you match these folk, it might be too far back to find. If one of the. Matches you in more places start with their tree and yours…

      I suggest you work with closer matches first. The ones with 90 or more cM and 3 or more segment, some of them large. Those relationships are generally findable

      And read a lot:-)..

  61. We received my husband’s ancestry.com dna results. His highest match is 1704cM. He believes this is with his first cousin: daughter of his father’s identical twin. But isn’t that number high for a 1st cousin? We are now doubting this is a cousin and wondering if this is a half-sister. How does identical twins and dna testing work? is there a difference in how we read the results?

    • The children of identical twins will look like half siblings in their DNA as one parent is effectively the same.So That result is normal for a first cousin fro. An identical twin.

  62. After sending my DNA to Ancestry.com a woman showed up as a close relative who I had never heard of or met. After contacting her, she shared with me that she was adopted and didn’t know anything about her biological parents. She is related to me through my father’s side. My father shares 2265 cM with her. My dad’s full brother shares 1647 cM with her. I share 1107 cM with her so after looking at Blaine Bettinger’s The Shared cM Project I came to the conclusion that she was a half sibling to my father from an affair my grandfather must have had. This was not received well so I also had my cousin (my dad’s full sister’s daughter) send in her DNA to Ancestry to get more clarification and her cM is 1555. My dad’s sister has passed away and my dad’s father has passed away so no way to get their DNA. Now here is where I’m confused, 1555 cM can either be half sibling or full aunt but half aunt was not highlighted on Blaine Bettinger’s chart. How can I know without a doubt where this women fits in our family? Also, my dad’s full sister mentioned above was rumored to have given up twins for adoption but we don’t know for sure because she never told anyone. Lots of family secrets exposed!!!! I would love to have your input on this!

    • It would be best if you all uploaded to GEDmatch for direct chromosome comparisons. If people are uncomfortable with a public database, then upload to family tree DNA. Not quite as much information there and everyone needs their own account but it will have the X matching and the exact segments which may be enough to figure this out.
      How much does your father share with his full brother and the niece? Your cousin shares more than the expected amount for a half niece, more like a half sibling which fits that story.
      Does this woman have matches on your father’s mother’s side of the family? That would confirm her being his sister’s child.

  63. My father shares 2,443 cM and 63 segments with his full brother. He shares 2001 cM and 59 segments with my cousin (his full sister’s daughter). I am trying to figure out if anyone from my grandmother’s side is showing up on our dna match lists. I can’t believe i didn’t think of that! I am in encouraging everyone to upload their dna to GEDmatch today. I just find it so odd that my dad shares 2265 cM and 56 segments with this new family memeber. Thank you so much for getting back to me! Your blog is an amazing place for a wealth of knowledge.

  64. I had a match on Ancestry of a woman who was adopted by closed adoption. We are close in age. We matched 1111 centimorgans on 45 DNA segments.Is that high for a 1st cousin? My known first cousins match in the 888 range on 35 to 40 DNA or so. One cousin, is both my 1st cousin & 3rd cousin , the cousin range fell in the usual limits! Could she be my maternal uncle child? I had 2 uncles who have no living children and they are deceased as is my mother. My 1st cousins on that side matched her too we don’t know of any adoptions in the family.

  65. Yes she could be your maternal uncle’s child. Although high, that is in range for a first cousin.
    He may not even have known that she existed. If you both upload to GEDmatch you could take a deeper look at this and check the X match.
    How many siblings did your mother have? Is a child of every one of them tested (where children are available)?
    Pass this on to your new cousin
    http://blog.kittycooper.com/dna-basics/help-for-adoptees/

  66. I have a match on Ancestry “M” who shares 2135 centimorgans across 57 strands of DNA. I know we are related on my dad’s side as we have other matches in common (distant, but I can confirm their relationship to myself and my dad). She messaged me and said she matched as a first cousin to “E” and “E” is my dad’s sister’s daughter. We have come to the conclusion that we are most likely half-sisters as we are 2 years apart in age and some other pieces would fit this scenario. Is there any other possibility?

  67. I have used the calculator you have as well as one with dnaHunters.

    In each case my Uncle and the “cousin” on 23andme show up as possibly 1/2’s or 1st cousin 1-removed. They share 19 segments, 5.07%, and 377cm.
    It is through this match that we believe we may be able to learn about my Grandfather who was a bit of a mystery.
    This “male cousin” though is of Haplogroup R-m417 where my Uncle tested as R-Z159 – this is through 23andme (is 23andme good enough to calculate this?). However, none of the shared segments are on the x-chromosome.

    My uncle was born in 1933 – however my grandfather David was around 43 (we have 3 different possible birth dates 1887, 1890, 1893) which means he very well could have had children elsewhere. **IF the child he had with someone else was a girl who then married a guy then had the baby (cousin born in 1946) that could explain things.
    The more difficult part is that this “cousin” doesn’t seem to believe there is much of a connection as the surnames are different. But we are relatively positive that David changed his or something.

    Because my father tested as R-Z159 a thought of doing a yDNA test was suggested by a friend.

    • Yes, if the mystery is on a Y line then please do at least a 37 marker test and better a 67 since it is an R group. You can do this test at family tree DNA (do me a favor and use my affiliate link to buy it https://affiliate.familytreedna.com/idevaffiliate.php?id=1529_0_3_5 0 )

      Often when someone asks this question, one R group (as listed by the end SNP) is downstream of the other so possibly the same group but that is not the case here. Your father’s Z159 is in the R1b subgroup while m417 is in the R1a subgrouping. Click on R on this page and then search for each SNP.
      https://isogg.org/tree/

      So this male cousin is not on the paternal line with your mystery. Thus your idea “the child he had with someone else was a girl who then married a guy then had the baby (cousin born in 1946) that could explain things.” Looks likely. Find out more about your new cousin’s mother’s ancestry perhaps her father of record was not her bio dad or perhaps he is your mystery grandad … get more of his descendants to test

  68. Ms. Cooper,

    I tested through 23andme and matched with a a likely first cousin that I didn’t know about. We have since then contacted each other and exchanged enough information to place on his small town both a maternal uncle and half-uncle of mine.
    The only other of my family members that tested is my father and they share 0 DNA.

    I am trying to convince my mother or one of her full brothers to do a 23andme kit; but they distrust the procedure. They don’t have a problem with having a possible new nephew; they just don’t seem to understand how 23andme works.

    To summarize, I am pretty much convinced new cousin and I share a grandfather (my mother’s father). I’m just trying to figure out if I should completely eliminate the possibility of us being full 1C.
    We share 590cM, accross 22 segments. With segments of less than 7cM removed, we share 577 cM. We also share four segments over 50cM:
    53.89, 53.99, 64.88, 85.06
    What do you think about this data? I know the numbers are on the low side of full 1C; but I have uncovered a lot of coincidences around that match being likely.

    Thanks,
    Marie

  69. Hi Kitty,

    My dad and sister both had their DNA done by 23 and me and discovered a previously unknown close relative named Mary. Mary shares 27.1%, 2016 cM with 37 segments with my dad and 14.4%, 1073 cM with 28 segments with my sister.

    23 and me listed Mary as my dad’s granddaughter and my sister’s 1st cousin. Mary contacted my sister and said her mother was born in 1933 and at one point her mother told her that she had a different biological father than the dad who raised her.

    My dad was born in 1925 and is obviously not Mary’s mom’s dad. My dad did not have kids until starting in 1958 that we know of. It’s possible he had a son who fathered Mary but given the age differences we think it’s highly unlikely.

    More likely is that my dad is Mary’s uncle and she is his niece as well as my and my sister’s 1st cousin. My father had 6 brothers but the oldest two were half-brothers from his father’s first marriage. They cannot be Mary’s father given the DNA shown above. My dad also had 3 full brothers who could be Mary’s father.

    The problem we have is that my dad’s mother also had another son out of wedlock before she married my grandfather. That son’s name was Dennis and his father was his great-uncle and his mother’s uncle.

    Can Dennis be Mary’s father? Or can we rule him out? He was more than a half-brother to my father biologically but how does that translate?

    Thanks for any help you can provide,

    Joe D

    • You really need to test more cousins to get the answer to this. It is not impossible that Dennis is her Dad, although highly unlikely as the shared DNA would usually be less (around 1300-1600), so likely it is one of your Dad’s brothers.

      Are any cousins on your mother’s side (1st or 2nd) tested? Your father’s side? You may need to compare them to Mary to find your answer. If the possible Dads cannot be tested, get a child of each to test if you can.

  70. A few months ago I signed up for Ancestry and when my DNA came back there was a “first cousin” match with 900cm. This gentleman lives over 2,500 miles away from my family here on the US’s west coast, and his parents and their ancestors were from a very small farming community and didn’t travel. He is my parents’ age, about 70.

    I have confirmed DNA matches to 7 of my 8 great-grandparents. (One great-grandma came from a very remote UK island and was a recent immigrant — she’s the one I don’t have matches with yet.)

    My mystery “cousin” believes that he must be my half-uncle (other relationships don’t make sense) and that his father must have been one of my parents’ fathers. Given birth dates and distance, I can’t see how that could be so. For the same reason, he cannot be my cousin. It IS remotely possible that a paternal grandfather or great-grandfather of mine, who were known to have done a little business travel to the midwest, could be HIS father, or grandfather. But he insists that he has DNA links to all four of his grandparents. But so do I, and more.

    Complicating matters, about 5 generations back we do have a shared ancestor on our paternal lines, and I suspect that there may be a few more of those as we dig deeper. In the 19th century, some of my ancestors lived in the state where he’s from (although not in that county) and our trees do share a few surnames (though not very recent ones).

    Is it possible that a DNA match with 900cm could be anything but a half-uncle or half-great-uncle to me? Could the large amount of centimorgans possibly be due to multiple shared ancestors farther back? I’m thinking, maybe he’s something like a second or third cousin (though I don’t know how yet) and the rest of it is due to sharing some DNA due to more distant shared ancestors. Is that possible?

    I don’t know if you have time to reply to this long comment. In any case, thanks so much for this marvelous website; I’ve learned so much from you!

  71. Have been looking for my brothers bio father for years. He recently tested with Ancestry and his closest match is with a woman who shares 1511 Cm’s. Her maiden name is the same as several of his male matches on FTDNA. He also matches another lady who is a niece of his 1511 match. this match is at 1094. Am I to assume that the 1511 match is his half-sister. They all live in the same state.

  72. Greetings Ms Kitty, I have what seems to be a complicated question.
    I am looking for a DNA relationship connected to my four times great
    grandmother. She was an immigrant from County Tyrone Northern Ireland. I just found a descendant from a family with the same surname who also immigrated from County Tyrone at about the same time and settled in VA. Therefore we are looking at small amounts of DNA from relatives who were born in the 1770s. We are both in GEDmatch and I also have the DNA of my sister and a distant cousin of this line in GED. When I compare our Ancestry kits, no relationship comes up, but when I compare our three Ancestry kits to his second kit via Family Tree we get a bunch of hits at the 3 CM and 2CM levels. ie my sister matches him on 5 chromosomes at levels of 3.6, 4.2, 4.6, 3.1, and 3.2 CMs. My matching is a bit less and my distant cousin matches only at the 2CM level. So, my question is, what does all this mean? Why matching with Ft and not Ancestry? Is this relationship real or just noise? I hope all of this makes sense and I really appreciate any help and answers. thanks so much

    • At that distance of relationship autosomal DNA is not very reliable. You might be better off finding a straight maternal line descendant on each line and doing an mtDNA test although since that can go very far back in time, it only answers your question when they do NOT match.

      Ancestry removes population specific autosomal DNA matching while family tree DNA shows very small and not necessarily relevant matching segments.

      Most segments smaller than 7cM are not real matches so we tend to ignore them. Even if those small segments that your sister shares are also shared with you and/or your cousin (triangulation), they may not be meaningful.

      see this post for an explanantion of false matching:
      http://blog.kittycooper.com/2014/10/when-is-a-dna-segment-match-a-real-match-ibd-or-ibs-or-ibc/#more-2309

  73. many thanks for the quick answer. not sure that we can find any straight maternal line descendants. guess we will just have to work harder
    on paper relationships. possibly not that many gibboneys in county tyrone in the 1770s. bill

  74. A 4th grandparent is just too far back for reliable autosomal results but if you get enough of her descendants tested, preferably the older generations, you may be able to get somewhere …good luck

  75. Hello Ms Cooper,
    I just filled out your questionnaire at the bottom of this page. The popup after I submitted says “half sibling or aunt/uncle or grands (doesn’t apply due to age difference)?”

    My match is someone Ancestry said was a likely 3 or 4C, who was adopted in 1958 and whom I have just started helping to find her birth mother. Am I misreading, or does this popup mean she could in fact be my half-sister? Thank you for your help!

  76. Miss Kitty, I have another question for you. My cousin and I are related via two brothers who are our great grandfathers. In Ancestry we only share 8 centimorgans and I know that that low level is possible for this relationship, but not usual. The problem is that we are more related than that. His great grandfather married his first cousin. That first cousin was also a first cousin of my great grandfather. She was the daughter of their maternal aunt. I am wondering if there is something wrong in our assumptions about parentage? I share many more centimorgans with
    several other cousins within this family who are descendants of other great grandparent siblings. The largest amount is 109 centimorgans. thanks so much again, Bill

    • William –
      So you are 3rd cousins plus 4th cousins on that family line. That low an amount is unlikely but possible, DNAPainter says it is 6.87% for just the 3rd cousin relationship.
      Of course, another possibility is that your cousin’s great-grandad’s father is not his biological father. Check if your cousin matches people on your side of the family and other great grandparent siblings not married to any cousins of theirs. Again, it could just be the randomness of DNA.
      If your cousin is not matching people just related to his g-grandad’s father’s side perhaps if you are both male line descendants of those brothers, a Y test will answer this question.

  77. Thanks so much for the quick answer and the ideas to check DNA
    relationships. This cousin will freak out if he thinks that he has carried
    the wrong last name since birth. I will have to be careful how I
    research this and let him see the DNA issues on his own. Bill

  78. Hi Kitty,
    I really enjoy your blog and all the DNA problem-solving you are able to do! I’ve bought you some wine as I need your expertise on something 🙂

    I’m helping someone with their DNA testing. This lady aged 84 (tested at 23andMe) has a new match on Gedmatch, a lady aged 85 who tested on (Ancestry). At first I thought first cousins but it could be a half-aunt? The grandfather had 5 sons and was then was widowed and needed a housekeeper.

    There is no shared X dna, so they are not sisters. Is that correct?

    They share 1015 cM across 17 chromosomes, some of it in very large chunks, including near total coverage of chromosome 22! The longest segments are 133cM on chromosome 12, and 128cM on chromosome 13 with some other chunks being in the 60s, 70s and 80s.

    When the ladies compared photos the likeness was uncanny. As one said “Like looking at a photo of myself!” One lady has known family history, the other didn’t know who her father was.

    The ladies are both excited to have made the connection and are planning to meet up. I have told them they are paternal first cousins but am I correct?
    I know the shared amount falls into both categories of yours and Blaine’s relationship analysis.

    Thanks so much 🙂

  79. The large segments would argue for the closer relationship – half aunt but she could also be child of one of those many sons.
    To figure this out it would be best to test each son (or a child of each son). The lack of X is never as conclusive a piece of evidence as having an X match. However it again argues for the half aunt scenario since both ladies would get X from their fathers and if their fathers are brothers it is very likely that they would share some X although not a for sure thing. for example I share 120cM with a first cousin whose Dad was my Dad’s brother…

    • Thanks Kitty. Will look into testing other paternal-side cousins.

      Even if nobody else tests, at least this lady now knows her father came from that family.

  80. Hi Kitty,

    I have a question regarding Y DNA. I’ve tested my Uncle out 111 markers, most other men have yet to test out that far. At 67 markers he has 5 matches with zero deviation, so 96% approximately they are related within 6 generations. I get that part. In corresponding with these men, I found one that has the exact same matches in common, with the exact deviations at this level of testing, neither of them has an additional person. Does this have any additional significance possibly suggesting a closer relationship?

    • I am not sure I understand your question. If they are 0 step matches then they should all have exactly the same matches as each other. This is a GREAT set of matches. The common ancestor should be findable in genealogical time.

      I have an R1b cousin who has a 0 step match that shares an ancestor born in 1603 while my Dad is a 3 step match on his line from a common ancestor in 1610. So this can vary widely but I would expect a 0 step match to be more likely recent, within 200 years.

  81. Do you know how to determine the chromosome analysis where two individuals have the same father, different mothers, but the mothers are sisters?

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