I match you on DNA, now what #dna


Moishe Miller
 

Dear Group, 

I am thankful for all the educational opportunities offered by this forum. It has helped me quite a bit. I took the JewishGen DNA course in August. I attended two DNA lectures via Zoom yesterday; one by the JGS of Colorado and one by the JGS of LI. Remote learning is a positive outcome of the quarantine all over the USA. Please do continue to post lectures, session, meetings, etc, that are open to members and non-members of the hosting entity.

Since I have my tests on Ancestry, MyHeritage, 23andMe, FamilyTreeDNA, GedMatch, GENI, etc, and also manage other people's tests, I get DNA inquiries every day. With what I have learned, I wanted to share how I now approach those DNA inquiries. My response now addresses the two general issues I face with DNA inquiries.
  1. DNA does not replace actual genealogical research
  2. A genetic tree is not as robust as a genealogical tree. This is because, beyond second cousins, it becomes possible to be related but not match with DNA (your small 6.5%, 3.25%, etc  might be different "pieces" for each descendant). In other words, beyond g-gp's, you do not necessarily inherit DNA from every ancestor you ever had.
My new method of dealing with "I match you on DNA" inquiries is to determine first, what is needed to figure out that match. Someone that does not know the names, places and dates for all four of their grandparents will likely not be able to determine if/how we are 2nd, 3rd, 4th or even more distant cousins.

Using a real example, with permission from one of the targeted persons, I have just received this inquiry for a test that I manage (I will call the inquirerer Harry):
  • Hi, I have DNA matches to two person's you manage on MyHeritage: Esther Bleier (born Steif). Estimated relationships: 1st cousin twice removed - 4th cousin?; DNA Match quality: 1.3% (92.5‎ cM); Shared DNA: 10 Shared segments; Largest segment: 20.6‎ cM. Also with Frederika [detail redacted to protect her privacy] 
(As an aside, these two people, Esther and Frederika, do potentially share common ancestry; this is why I had them both tested. When my grandmother was a young teenager, she left home and lived by Esther's parents, the Steif family, who married her off. My grandmother had told us she was related to them. I have not yet determined how.)

Harry and I had some basic dialog where I asked where Harry's ancestry was from, and some surnames. Nothing seemed to match Esther's known ancestry.

So I suggested to Harry:
  • Go to https://dnapainter.com/tools/sharedcmv4
  • For your match with Esther Bleier, put in your total cM matching, which is 92.5.
  • The combined top two results indicate it is 63% likely that you match Esther as some form of 2c or 3c.
  • To match as a 2c, you need to know all of your 8 g-gp's and compare each one to her 8 g-gp's for surname, time-period lived, and location compatibility.
  • To match as a 3c, you need to do the same thing, only with your 16 g-g-gp's.
  • For "Once-Removed" relationships, you would move up or down a generation, to match the predicted relationship (such as 2c1r)
  • I gave Harry the pedigree for Esther Bleier at https://www.geni.com/family-tree/index/6000000001156042118
  • It does have Esther's 8 g-gp's listed.
  • It does not have enough of her g-g-gp's listed, in case it is a 3c match,
  • Unless Harry is lucky, or either of us does more paper-trail research on both his tree and Esther's tree, we may not figure it out.
  • You can repeat the same process for determining other matches.
  • Since Frederika's match does not triangulate with Esther's, we don't know if the ancestry between the Harry, Esther and Frederika is shared.
Anyone can help to make it simpler to find the genealogical connection of a DNA match, on most platforms. Create a tree of at least 15 people, comprised of you, your parents, GP's and g-GP's (if you know them of course). And, on FamilyTreeDNA, add the detail described in the article at https://dna-explained.com/2020/07/07/earliest-known-ancestors-at-family-tree-dna-in-3-easy-steps/

I hope that by combining DNA Research with Genealogical Research, we can all help to expand what we know of our ancestry and history.

Wishing everyone a Shana Tova,
Moishe Miller
Brooklyn, NY
moishe.miller@...
JGFF #3391

Join main@groups.jewishgen.org to automatically receive all group messages.