Sally responded to this post:

"I recently got my results from a DNA testing product I signed up for. The information it gave me on my ethnicity told me pretty much what I knew from my own research about the geographical origins of my ancestors. (The map it provided, was almost the same as one I did myself when writing up my family's history). The results also included about 300-plus individual "matches." All of them were listed as "potential" 3d and 4th cousins. I sampled about 20 who had public trees, but none of them included any surnames that I have in my own tree. So, I assume those results only mean that if you go back as far as DNA can take you, just about everyone is a relative."

Sally Bruckheimer Tue, 7 Oct 2014 posted:

I am a Molecular Geneticist and genealogist, so I know more than most about what DNA can do and not do. When you go to buy a used car, the salesman tells you all about the 'little old lady who only drove it to church on Sunday' - puffing or, in my opinion, lies. Well the DNA companies have the same problem, especially with Jews.

A recent article in Nature Communication models the Eastern European Ashkenazi Jewish population as arising, today, from about 350 people or so, 600-800 years ago. That means that all of the descendants of the Ashkenazi Jews (Galicia, Russia, what is today Poland) are at most 30th cousins. But since in 700 years or 28 generations a person has 2 to the 28th power or over 268 million ancestors, it is easy to see that all Eastern European Ashkenazi Jews are descended from those all 350 of those people many times. And it also means that we are much more closely related to each other than 30th cousins.

Ancestry has recently admitted that it matched ALL Jews with each other (but it will do better in the future). This is an amazing admission, but not surprising, as it is virtually impossible to do 'genetic genealogy' as second or third cousins share little DNA. The funny thing about DNA is that on one scale, DNA testing for immediate families is easy, and determining ethnic origin is easy, in between is not so easy. Since Ashkenazi Jews are all so closely related, it is especially difficult to winnow out all the DNA to find people who are second or third cousins.

So, in spite of all the hype, DNA testing is not the 'easy genealogy' that they lead you to believe. You get a list of the 300 or whatever 'best matches' - are they cousins-Puffing? If you and they are Ashkenazi Jews from Eastern Europe, then they are cousins - somehow. But this isn't genealogy. If you find a third cousin, but you don't know where your parents came from, and the 'third cousin' doesn't know either, how would you tell? And those Eastern European Ashkenazi Jews didn't have surnames, by and large, before the first part of the 19th century, so you have little chance of connecting with cousins by common ancestors before that (major rabbinic families are better known). Sorry to disappoint you, but you are right. You spent good money for a list of 300 people who are cousins, but you would post on JewishGen and reach a lot more than 300 cousins.
Sally Bruckheimer Princeton, NJ

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