DNA Research #DNA Jewish Endogamy - A Convenient Scapegoat #dna


Jeffrey Mark Paull
 

The information below is in response to David Goldman's post. I
believe that the information will be of value to the readers of DNA
Testing Digest.

---
From: "David Goldman" <lugman@...>
Date: Sat, 4 Aug 2018 22:09:59 -0400

Hello, everyone at the DNA Group. I was notified of a new "extremely
high" probability of a 3rd or 4th cousin match >from Ancestry with 102
centimorgans on 7 segments. However, when I was in touch with that
match we shared all the family names we could think of and none of
them were the same. The "match" would mean that our grandparents or
great-grandparents were first cousins. My known last names go back to
my great-great-grandparents, and even a couple more beyond that. So
given this "false positive" I would have to strike this up to the fact
of high endogamy among Ashkenazi Jews, such that perhaps we had
ancestors several hundred years ago who were the same. But for
purposes of genealogy for most of us, such speculation is probably
rather meaningless.

David Goldman
NYC
___

Your situation comes up quite often, especially among Ashkenazi Jews.
Oftentimes, when people of Jewish ethnic ancestry cannot identify their
common ancestor, they often chalk it up to "Jewish endogamy," as you
did. But, this is not necessarily the correct explanation.

The reason that this situation occurs so often among Ashkenazi Jews is
not necessarily due to Jewish endogamy, although that may play a role
at very distant relationships. There is, instead, a much simpler and
more obvious explanation ... that generally speaking, Ashkenazi Jews
have very limited knowledge of who their ancestors were.

Let's go back to your statement: "However, when I was in touch with
that match we shared all the family names we could think of and none of
them were the same." The key phrase in that statement is: "all the
family names we could think of."

Let's take the example of you having a genetic match at either the 3rd
or 4th cousin level. At the 3rd cousin level, you share one pair of
great-great-grandparents out of a total of eight pairs. At the 4th
cousin level, you share one pair of 3rd-great-grandparents out of a
total of sixteen pairs. Do you know all 16 of your great-great-
grandparents, and all 32 of your 3rd-great-grandparents, including
their maiden names? Very few Ashkenazi Jews do.

What typically ends up happening is that Jewish genetic matches compare
notes, just as you did. They rattle off a list of surnames that they
are familiar with, which represents only a partial subset of the total
number of lineages that they are descended from. Their genetic match
does the same thing for the partial subset of lineages that they know
about. More often than not, these two partial subsets do not overlap.

If all Ashkenazi Jews had family trees that extended back at least five
generations to their 3rd-great-grandparents, there is no doubt that they
would be able to identify a large percentage of their 2nd, 3rd, and 4th
cousin genetic matches through autosomal DNA testing, the same way that
many non-Jews are able to do. Jewish endogamy plays very little role at
these relationship levels, as demonstrated by autosomal DNA studies.

See:
https://www.academia.edu/7841372/Differences_in_Autosomal_DNA_Characteristics_between_Jewish_and_Non-Jewish_Populations
[or https://tinyurl.com/ya6oj6nj --Mod.]

An additional complicating factor that enters into the equation for
Ashkenazi Jews, involves their surnames themselves. Most Ashkenazi
Jews acquired their surnames in the early part of the 19th century in
the Russian Empire, where, for reasons related to the Jewish surname
laws, many related people acquired different surnames, while other
non-related people acquired the same surname. Adding to this
complication is the fact that many Ashkenazi Jews changed their
surnames upon immigrating to America. This surname instability is a
complicating factor that most non-Jews do not have to contend with,
and again, it has nothing to do with Jewish endogamy.

See:
https://www.academia.edu/14679754/The_Jewish_Surname_Process_in_the_Russian_Empire_and_its_Effect_on_Jewish_Genealogy
[or https://tinyurl.com/y7kbmc3x --Mod.]

I hope that this information helps to clarify the picture a bit.
Jewish endogamy ends up being a convenient scapegoat that is used to
gloss over or ignore a myriad of other, more fundamental problems, which
are inherent to the practice of Jewish genealogy. Recognizing what the
real problems are enables us to move forward to confront those challenges.

All the Best,

Jeffrey Mark Paull

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