New DNA Tools and Blog from a Scientist at Cornell

Much of the work to build tools and write articles to help testers with their DNA results has been done by citizen scientists, bloggers, computer programmers, and scientists from other fields like Andrew Millard (behind the WATO math). In an exciting development, Amy Williams, a computational biologist at Cornell University, has built a few DNA tools, with more to come, and started a blog at

Her blog article titled “How often do two relatives share DNA” is particularly interesting. It includes the beautiful chart shown below which is created from simulations. Click it to go to the actual page where you can mouse over the columns to get the detailed numeric breakdowns.

Chart of How Often 2 Relatives Share DNA from

The other article on her blog has a detailed explanation of what a centiMorgan is, the measurement used for DNA segment sizes (click here). I usually recommend not worrying about the exact definition since it is a measure of the frequency of recombination rather than a physical length. It is important just to know that there is not a one-to-one relationship between the cM and the sizes shown in the chromosome browsers. On the those charts, the same cM amount looks smaller at the ends of chromosomes than it does in the middle because recombination is more active on the ends.

The final statement of that article is: “In an upcoming post, we’ll talk more about cM lengths of DNA and how recombination leads more distant relatives to share fewer segments that are also on average smaller than those that close relatives share.” Something to look forward to!

Now to take a look at the tools that are available there so far.

Of particular interest to adoptees is the maternal versus paternal predictor for half siblings or grandparents. I tried it out on a number of half sibling pairs who I have helped in the past.

Here is the prediction created for a brother and sister who share the same father but have different mothers, using the comparison of their segment data from 23andme:

However I discovered  number of minor usage issues when trying to use data from the different DNA testing sites.
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Please Help Collect Sibling DNA Statistics

I need more data from full and three quarter siblings that are either tested at 23andme or have uploaded to GEDmatch. Ever since I published my article on why full siblings don’t share more DNA, I have been getting inquiries from people who are concerned that they are only ¾ siblings, so I would like more cases in order to help them figure that out.

My article (click here for it) included the insight that if you sum the FIRs (fully identical regions) and HIRs (half identical regions) of full siblings you get a result of about 3600 cM. This is roughly the same amount shared with a parent, thus a true half of the inherited DNA. My article also discussed the expected numbers for ¾ siblings.

Here is the form to help me collect this information, Please do not include the X if you are using 23andme. Below are some more instructions if you need them.

If you are using GEDmatch, the instructions for collecting this data are in my previous article, click here. For the 23andme instructions click the read more below.
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Comparing Ethnicity Estimates Across Companies

Both Ancestry and FamilyTreeDNA have recently updated their ethnicity results. As much fun as it is to look at your ancestry composition, those estimates do not really reflect the populations of today’s countries, but rather human migrations hundreds of years in the past. Therefore the big picture is more accurate than the smaller areas. Examples that I have found to be realistic are North versus South Europe or East versus West versus South Asia.

To the left is a simple pie chart showing the known ancestry for my brother and myself for the last 300 years or so. Our father was Norwegian American, documented back to the 1600s, and our mother was born in Munich to a Jewish father and German (Bavarian) mother. In 2016 I wrote a blog post showing how my brother’s ethnicity appeared at a number of DNA companies and third party sites (click here for that post). This post will look again at the ethnicity predictions for each of us from the main testing companies.

One thing I always find interesting is that they all show my brother Shipley with less DNA from our Jewish grandfather than I have. The variations between full siblings can be quite large.

Let’s look at the new Family Tree DNA results first:

My Origins at Family Tree DNA for my brother and myself

Nice and simple but not very accurate. We have no British ancestors in the last 500 years that we know of. However there is no such thing as German DNA because that area was a crossroads. It usually shows up as French, Scandinavian, British, or even Eastern European. Jewish DNA is quite distinct due to centuries of endogamy. Interestingly, our Jewish never comes out at the expected 25%. All the companies show me with more than that and my brother with less. Although you inherit half of your DNA from each parent, they do not have to pass you an equal amount from each of their parents.

Here are our results at MyHeritage:

Our ethnicity predictions at MyHeritage

MyHeritage is an excellent site for working with your DNA since it includes a chromosome browser that shows triangulations and it also looks through user trees to try and figure out your relationships to your DNA cousins. However, although their ethnicity estimates have improved over time, like Family Tree DNA, they incorrecty find lots of British Isles DNA for us. They call it Irish, Scottish, and Welsh. The Jewish component is only few percentage points different from Family Tree DNA.

Frankly I find the estimates at 23andme and Ancestry more accurate.

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Genetic Genealogy News Round Up

2020 has been a horrible year so far, in more ways than I can count. However, one good thing is that more of us are staying at home working on our family history and using DNA tools to help with that. Here is my summary of the latest genetic genealogy news for you, both the good and the bad. First the good…

MyHeritage did a new run of their Theory of Family Relativity so go look if you have any new connections with theories. Unlike Ancestry which seems to run theirs almost every night, MyHeritage only runs it every few months but it is more detailed. Click here for my blog post about this feature.

Family Tree DNA updated their ancestry composition estimates to version 3 which includes 66 new reference populations. Click here for the blog post Roberta Estes wrote about it. I will write a post soon that compares results at all the companies for my brother like I did six years ago (click here). For my extended family, version 3 is not an improvement, although I like the new Magyar population predicted for us which fits into my 25% Bavarian ancestry.

My new ethnicities at family Tree DNA. My father was Norwegian and my mother German (half Jewish). No British.

According to a FaceBook post in the GEDmatch user group, Verogen announced a number of GEDmatch improvements coming in Q4 at the ISHI (International Symposium on Human Identification) conference including enhanced security for GEDmatch and a modernized User interface.

Ancestry also moved that wonderful new Longest segment feature (click for my blog post about it) and at first I could not find it. An appeal to the hive mind at FaceBook resolved my problem. As shown in the image below, you have to click the amount of shared DNA in blue to see that and another new feature, the “Unweighted shared DNA. That is the amount of matching DNA before their algorithm removes the DNA assumed to just be from your particular population group. That algorithm has vastly improved my Jewish side matches, as it would for anyone with endogamy in their tree.

My known third cousin who shares Jewish great great grandparents with me

Now for the bad news.
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New Ethnicities at Ancestry

Ancestry just did a major update to its ancestry composition estimates based on DNA tests. I was sad to see that my brother and I lost all our German. That seems strange and incorrect, as our grandmother was Bavarian. Now her ethnicity appears to be some combination of Swedish, English, Norwegian, and Eastern European. Germany was a crossroads between Eastern, Western, and Northern Europe so one expects to be very mixed, still I was sorry to see her German and Italian go away. On the other hand, I am pleased to now be 49% Norwegian since my father was the son of Norwegian immigrants in Brooklyn and I am also happy to be even more Jewish.

Kitty Cooper's ethnicity at

Kitty Cooper’s ethnicity at

The ethnicity comparison with my first cousin who shares my German grandparents (one Jewish, the other Bavarian) seems to show the new view of my grandmother’s ethnicity

Today was the day that I finally got the email from Ancestry announcing the update to my ethnicity estimates. Vivs, an administrator of one of the many DNA FaceBook groups I follow, pointed out that this is an ideal time to send messages to DNA relatives you have not heard from as they may well log in and see your message because of that email. In fact, just now, I got a reply from a cousin I had messaged over a year ago!

Clicking on the button that says Learn more in Ancestry‘s email took me to a page that explained the update and included a nice map. Here is a quote from there with the essence of the changes:

“In our latest update we have been able to break larger regions—like England, Wales & Northwestern Europe; Ireland & Scotland;  Italy; China; Japan; the Philippines; Cameroon, Congo & Southern Bantu Peoples; and Eastern Europe & Russia—into smaller, more precise ones.”

Of course, I had to go look at some of the people I have helped who have interesting ethnic mixes.
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