"Ashkenazi" Admixture?

[Katydid]

My mother-in-law is of 19th century German heritage (ancestors from present-day Germany and Poland); as such, she doesn't have a lot of Family Finder matches, i.e., approximately 150.

Interestingly, about 1/3 of her matches are Jewish, all on one chromosome and a couple on her x-chromosome. Her first cousin shows almost the same set of matches in both places, plus a few other Jewish matches elsewhere.

I had initially thought there was most likely a shared non-Jewish ancestor between my MIL and the Jewish matches, as her Population Finder results showed 100% European. However, comparing her results with some of her Jewish matches in Gedmatch, I've been struck by a couple of things that are making me reconsider that assumption:
1. some of those matches have a predicted MRCA with her on Gedmatch of 4-5 generations ago (rather recent)
2. admixture analysis using the Eurogenes "J" test seems to show an "Ashkenazi" segment in the region where she matches these Jewish cousins.

I'm wondering if anyone can tell me how meaningful the admixture result is: is it reasonable to assume that the shared DNA came from a Jewish ancestor, or am I just seeing "noise"?

Here's a screenshot of the region in question. The top chromosome is my MIL, the second is one of her Jewish cousins matching between ca 180-190, and the third is the "comparison" of the two regions.

[josh w.]

It could go either way, shared non Jewish ancestor or shared Jewish ancestor. The fact that a couple of cases involved X suggests that it might be on her mother's side. Recent research suggests that Jewish Mtdna resulted from admixture with European host populations --Jewish men married non Jewish women. It could have been fairly recent. Combined with a full European PF, I am inclined to think the common ancestor was not Jewish, but I am not confident. Has she been Mtdna tested. Uploading results to Gedmatch + Oracle might give a clearer picture.

[Katydid]

The "Jewish connection" is indeed on her maternal side (as her first cousin is a maternal cousin), but we have not done a mtDNA test. Her first cousin incidentally shows roughly 7% Middle Eastern in Population Finder, although of course that may not mean anything.

[Edek]

Katydid,

Ashkenazim should be consider as an European ethnicity, even though they have historical origins in the Near East. Ashkenazi Jews have been in Europe for more than 2000 years and they are highly admixed (with a big component from Mediterranean area and also from Central, Eastern Europe in their gene pool). Recent studies show that 80% of the maternal ancestors of modern Ashkenazi Jews were European converts.

Just as an example, I have my family tree well documented until 1750. Both sides of my family were Roman Catholic. Now comes the paradox. FTDNA says that I'm almost 40% Middle Eastern Jewish and 1/4 of my genetical cousins (4th-5th cousins) on FTDNA are Ashkenazim. Ironically, 2 of them have ancestors who were from the same village where some of my Polish ancestors used to live. But, when I uploaded my FTDNA raw data file to GEDmatch and ran the tests, I have no % of Ashkenazi ancestry. On 23andme my results also confirm that I do not have any Ashkenazi ancestry, but on the other hand I do have lots of Ashkenazi genetic cousins (4th-5th).

Throughout the history there were always cases of interethnic marriages and conversions. Most frequently for social and religious persecutions Jews converted to Christianity, but there were also conversions to Judaism.

** Note that on 23andme Ashkenazim are classified as European, not as Middle Eastern people, what seems to be more coherent in my opinion.

[Katydid]

OK, I think I know/understand all of this, but what should I make of the "Ashkenazi" component on her chromosome segment that matches her Jewish cousins? What distinguishes "Ashkenazi" from other J-test categories such as Middle Eastern, Eastern Mediterranean, Eastern European, etc. that have contributed to the European Jewish gene pool?

Katydid,

Ashkenazim should be consider as an European ethnicity, even though they have historical origins in the Near East. Ashkenazi Jews have been in Europe for more than 2000 years and they are highly admixed (with a big component from Mediterranean area and also from Central, Eastern Europe in their gene pool). Recent studies show that 80% of the maternal ancestors of modern Ashkenazi Jews were European converts.

Just as an example, I have my family tree well documented until 1750. Both sides of my family were Roman Catholic. Now comes the paradox. FTDNA says that I'm almost 40% Middle Eastern Jewish and 1/4 of my genetical cousins (4th-5th cousins) on FTDNA are Ashkenazim. Ironically, 2 of them have ancestors who were from the same village where some of my Polish ancestors used to live. But, when I uploaded my FTDNA raw data file to GEDmatch and ran the tests, I have no % of Ashkenazi ancestry. On 23andme my results also confirm that I do not have any Ashkenazi ancestry, but on the other hand I do have lots of Ashkenazi genetic cousins (4th-5th).

Throughout the history there were always cases of interethnic marriages and conversions. Most frequently for social and religious persecutions Jews converted to Christianity, but there were also conversions to Judaism.

** Note that on 23andme Ashkenazim are classified as European, not as Middle Eastern people, what seems to be more coherent in my opinion.

[Edek]

It would be impossible to say just by comparing the segments if they are related on the Ashkenazi side or not. The fact is that between ca 180M to 190M your mother-in-law has a significant amount of Eastern European and Atlantic component with a small Ashkenazi ingredient. While her genetic cousin has a significant amount of Ashkenazi and Eastern Mediterranean component with a small Eastern European element. In this case they could possibly share either an Ashkenazi or Eastern European ancestor.

In brief words, studies have proved that even though Ashkenazim are highly admixed (Middle Eastern, Mediterranean, Southern, Central and Eastern European components), the endogamy among them is the main factor which contributed to their arise as an ethnic group. That's what distinguishes them from the other populations you've mentioned.

[josh w.]

OK, I think I know/understand all of this, but what should I make of the "Ashkenazi" component on her chromosome segment that matches her Jewish cousins? What distinguishes "Ashkenazi" from other J-test categories such as Middle Eastern, Eastern Mediterranean, Eastern European, etc. that have contributed to the European Jewish gene pool?

Ashkenazis are only distinct by the particular combination of geographical components that they display. Actually they are not that distinct because Lebanese and Southern Italians show very similar combinations. Compared to these two groups, Ashkenazis perhaps have more of a northern European component.

Since the cousin shows Ashkenazi admixture, I am now less certain that the common ancestor was not Jewish.

[Katydid]

OK, here's a comparison between my MIL and another Jewish match; the latter matches her DNA between about 186M and 200M. In this case, the shared admixture present is basically Ashkenazi and Middle Eastern.

It would be impossible to say just by comparing the segments if they are related on the Ashkenazi side or not. The fact is that between ca 180M to 190M your mother-in-law has a significant amount of Eastern European and Atlantic component with a small Ashkenazi ingredient. While her genetic cousin has a significant amount of Ashkenazi and Eastern Mediterranean component with a small Eastern European element. In this case they could possibly share either an Ashkenazi or Eastern European ancestor.

In brief words, studies have proved that even though Ashkenazim are highly admixed (Middle Eastern, Mediterranean, Southern, Central and Eastern European components), the endogamy among them is the main factor which contributed to their arise as an ethnic group. That's what distinguishes them from the other populations you've mentioned.