Tuesday, 27 March 2018

Genetic detective work: Does my mother have Ashkenazi Jewish ancestors?

My mother has taken the autosomal "Family Finder" test at Family Tree DNA (FTDNA). Her matches have been a great help in piecing together some lines on her family tree, and especially in digging out our Romani connection. My mother's match list also seems to verify paper trails on her paternal grandfather's side, including our Forest Finn ancestry. In many ways, my mother's results were quite clear-cut and more or less as expected.

However, there is a mysterious side to my mother's results: Her admixture. Her FTDNA myOrigins results include a full 1% which the program is unable to classify. That 1% is labelled as "Undetermined Region", meaning that it could be either European, Asian, African, Oceanian or Native American. In other words, the origin of this 1% of my mother's genetic background is completely unknown.

1% is, in theory, roughly equivalent to a 4th or 5th great-grandparent. It is a rather significant amount, especially in the context of other admixture analyses such as 23andMe which sometimes reports admixture down to 0.1% with good confidence. My mother, however, has not tested at any other company except FTDNA, so we don't have an official second opinion on her genetic admixture.


Ashkenazi Jewish?

Immediately after FTDNA had updated their myOrigins analysis from version 1.0 to 2.0, my mother's results looked somewhat different. She did have 1% Undetermined Region, but she also had an additional region colorized on her map. It was the region around Poland and Ukraine. Those who are experienced with myOrigins recognize this blob as belonging to the "Ashkenazi Jewish" admixture category. And indeed, when I clicked on the blob, it was the Ashkenazi info box that appeared at the bottom of the screen.

The Ashkenazim, for those who do not know, are a distinct community within Judaism. They are genetically distinct enough for the genealogical DNA testing companies to be able to distinguish them as a separate ancestral cluster, just like Scandinavians, Finns, etc.

Here is a screenshot of my mother's results when she still had the mysterious Ashkenazi blob and info box on her map:


(The Ashkenazi blob is blue; the reason why it seems blurry and greyish in this screenshot is that my mother also has Eastern European admixture, and those two blobs are on top of each other.)

Could this blob mean that my mother's Undetermined percentage might in fact be Ashkenazi? Could it be that the amount was too small for the analysis program to assign it with confidence?

I wrote to FTDNA, and the reply I got was that this was a technical error. The blob on the map is now gone, "fixed" by the people behind the scenes. However, I still wonder why that particular error happened. I have not heard of anyone else who got mysterious Ashkenazi blobs connected with their Undetermined percentages. If you have experienced this, or if you know someone who has, please leave a comment below.


GEDmatch

Since my mother has only tested at FTDNA, the only way to get a solid second opinion on her admixture is to use the calculators at GEDmatch. (Her data is on MyHeritage as well, but their admixture estimates are too coarse-grained to be helpful in this case.)

The GEDmatch calculator Jtest was specially built to estimate the likelihood of Ashkenazi Jewish heritage based on DNA. In Jtest, my mother gets 2.2% Ashkenazi, which is more than zero but below the noise threshold (around 5% for Europeans with no known Jewish heritage).

However, my mother has a very significant Ashkenazi segment on chromosome 15. It seems like most of her Ashkenazi admixture is concentrated in this segment. The fact that it is so concentrated, and not spread out in tiny bits (which could be statistical noise), strengthens the likelihood that my mother's Ashkenazi admixture is real.

Screenshot of my mother's Ashkenazi segment on chromosome 15 (light green). Note that this screenshot does not show the full length of the chromosome.


Jewish matches

Admixture results should always be taken with a grain of salt, but their veracity can be tested by looking at a person's cousin matches. If one is assigned a certain percentage of a biogeographic category, and also has a significant amount of matches whose heritage is from that particular ethnic group or area, this is an indication that the admixture estimate may be correct. What should be considered "significant" is, of course, debatable. Like all genealogy, DNA results are open to human interpretation and human error.

Interestingly, my mother does have quite a few matches of Ashkenazi Jewish origin. In her match lists at GEDmatch and FTDNA I have found a total of 10 matches who are very likely Ashkenazi Jewish, as well as an additional 11 matches who are possibly Ashkenazi Jewish.

Looking more closely, I have found a triangulating group of Ashkenazi matches on my mother's chromosome 2; the triangulating segment is 14.1 cM long, which is not insignificant.

My mother does not, as yet, have any clearly Ashkenazi triangulation groups on the segment on chromosome 15. However, the fact that she has a number of Ashkenazi matches on others segments - and especially the triangulating group on chromosome 2 - does, in my opinion, make it more likely that my mother has actual Ashkenazi ancestry and that her Ashkenazi segments are real, including the one on chromosome 15.


Conclusion and further thoughts

It is not completely proven, but looking at the genetic data, I believe it is likely that my mother has a semi-distant Ashkenazi Jewish ancestor, and that her 1% Undetermined Region at FTDNA might in fact be Ashkenazi DNA.

At least two of my mother's (relatively) certain Ashkenazi matches are from Russia. She also has Russian matches, 14 in total (on FTDNA, GEDmatch and MyHeritage), of which several triangulate in various groupings. This, combined with her 5% Eastern European admixture at FTDNA, indicates that my mother's Jewish ancestry probably comes from an intermediate ancestor who was of primarily Eastern European (non-Jewish) descent. 5% plus 1% gives 6%, which is equivalent to a great-great-grandparent.

This begs the question: Could my mother have an Eastern European great-great-grandparent of partly Jewish descent?

There is a family story that my mother's great-grandmother Signe was of Russian descent, but there is uncertainty as to whether that story is connected to our bloodline or to Signe's stepfather's family (the Walentin family from Denmark). However, in light of the genetic data, the Russia story is too significant to ignore.

Signe as a young woman, probably around 1905

On paper, Signe has no known Russian or other Eastern European ancestors. In other words, if the story is true, there must be a non-parental event (NPE) somewhere in her line. If we take FTDNA's admixture estimate at face value, then Signe herself must be the daughter of a Russian man.

I am exploring this possibility, but hard evidence is lacking. Several Russian men - including several Ashkenazi Jews - were living in Oslo at the time of Signe's conception (1885). One of these Russian men, a naval officer, was living in a hotel very close to the hotel where Signe's mother worked. If I ever manage to solve the mystery of our Eastern European/Jewish roots and the story of Signe's alleged Russian ancestry, I will definitely write a separate blog post about it!

If you have any thoughts or ideas, please do not hesitate to leave a comment.

UPDATE: After having corresponded with Jewish genealogists, I must conclude that it is unlikely that my mother has recent Jewish ancestry. If there is any Jewish ancestry, it must be quite far back in time.

3 comments:

  1. Thank you for this! When I do the Jtest on GedMatch I get 2.81 for my Ashkenazi score. Ancestry gives me trace amounts of Eastern Europe (besides 21% Finland/Western Russia) and Geneplaza gives me 30% North Slavic (Belarus, Estonia, Lithuania, Mordovia, Russia, and Ukraine.) On chromosome painting on GedMatch, I get 12.0 as the largest Ashkenazi segment on chromosome 2 and 10.1 on chromosome 5. It looks very close to what your mother has.

    When I run the MDLP World-22 admixture, I get a wild mix on the Oracle 2 population mixed mode of in the 90%s of Swedish and then 6 to 9% of Jew Francestrale, Sephardim, Ashkenazim, Jew Algeria, Jew Morocco, Jew Tunisia, etc. as the second population. Ancestry says I have trace amounts of Italy and Greece, and FTDNA and a couple of others list Southern Europe and the Iberian Peninsula.

    I went on a FTDNA forum and asked about this and was basically "pooh-poohed" by the resident Jewish experts. They said that the Jtest wasn't accurate and to ignore the other admixture calculator. Hmm...What I would like to know is how you determine if a match on FTDNA has Ashkenazi in their origins. FTDNA doesn't show admixture breakdowns (that I'm aware of.) Are you looking for them based on surnames, or ? I would really be interested to know. I have stumbled across some matches who had high scores on GedMatch for Ashkenazi but am not sure if that is a more recent occurence for them and not related to an ancestor we share. Thanks, Miriam!

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  2. Thanks for commenting! Yes, I base it mostly on surnames, and in some cases I've corresponded with the person directly.

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  3. Thanks for your reply. I did correspond a while back with a FTDNA match whose ancestors came from the same area of Germany (Wurttenberg) that mine did on my father's side. In fact, his surname was Wurttenberg. He did have some Ashkenazi Jewish ancestors. And I just ran a close match of mine (again from my dad's side) through the Gedmatch Jtest and she has a score of over 5. Recently I found out my dad's direct male ancestors had been Mennonites who moved a lot through Germany and France because of persecution before coming to America in the 1700's. I wonder if perhaps there may have been a Jewish connection somewhere in there that prompted an ancestor to switch to that particular religion. From what I've been able to find, the Jews and the Mennonites had certain beliefs in common and because of persecution they often found themselves in proximity. It's a thought, anyway. :)

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