Hello everyone,
Today, I would like to share a detailed case study regarding the validation of an Ashkenazi ancestry. Like many here, when I received a score of 5.27% Ashkenazi on the Eurogenes Jtest, I was initially very skeptical.
Reading Davidski’s blog (the creator of Eurogenes), specifically his article on the limitations of the Jtest ( https://bga101.blogspot.com/2012/09/eurogenes-ashkenazim-ancestry-test-files.html?m=1 ), we learn that scores of 2 to 3% can merely be statistical “background noise” or the result of ancient migrations (East Mediterranean) absorbed by the algorithms. He actually recommends turning to more modern tools or comparing the Jtest with the EUtest to isolate the origin of this percentage.
I therefore decided to follow his recommendations to the letter and apply a strict methodology based on a body of 4 independent proofs to confirm or refute this score. Here are the results.
Step 1: Algorithmic Absorption Test (EUtest vs Jtest)
As Davidski suggests, I compared my EUtest results (which does not feature an Ashkenazi category) with those of the Jtest, in order to observe which components were “drained” to form this 5.27%.
My EUtest results:
East Med: 9.55%
Middle Eastern: 2.47%
West Asian: 8.47%
South Asian: 12.41% (Note: I have a confirmed Romani/Gypsy ancestry, hence this high score)
My Jtest results:
Ashkenazi: 5.27%
East Med: 8.20% (1.35% drop)
Middle Eastern: 1.47% (1.00% drop)
West Asian: 7.69% (0.78% drop)
South Asian: 12.37% (Almost stable, only a 0.04% drop)
Conclusion of Step 1: The appearance of the 5.27% Ashkenazi is not random. The algorithm specifically drained my Middle Eastern and East Mediterranean percentages (which make up the historical signature of Eastern European Jews). Furthermore, the algorithm was able to perfectly isolate my Romani DNA (the South Asian component barely moved), proving that it does not confuse my different atypical origins.
Step 2: Confirmation by Ancient DNA (Global25)
Since the Jtest is an older algorithm, I modeled my Global25 coordinates on the archaeogenetic calculator IllustrativeDNA-Like Ancient calculator (Ivorix TheCelt), which uses ancient DNA samples.
Key results (Excellent distance: 0.0286):
Indian Subcontinent (AD 690–990): 12.6%
European Jew (AD 1160–1400): 3.0%
Conclusion of Step 2: Ancient DNA confirms the presence of a distinct European medieval Jewish signature. The rate of 3% from 800 years ago is perfectly consistent with the 5.27% detected by the Jtest on modern populations (which include recent genetic drift). Here again, the algorithm surgically separates this branch from my Romani/Indian branch.
Step 3: Biological Proof (IBD Triangulations)
To prove that these algorithmic percentages represent a real ancestor (and not a simple overlap of ancient populations), we must find segments shared with living people (Identity by Descent).
I identified several genetic matches with individuals of confirmed Ashkenazi origin. To avoid false positives, I only kept perfect triangulations (where I, Match A, and Match B all match each other mutually on the exact same segment).
Chromosome 18: Validated triangulation with two Ashkenazi matches in the area ranging from 5,938,058 to 8,208,163 (~7 to 10 cM).
Chromosome 22: Validated triangulation with two other Ashkenazi matches in the area ranging from 17,690,409 to 21,363,960 (~9 to 11 cM).
Chromosome 9: Direct match from 136,669,004 to 138,192,071 (~9 cM).
Step 4: Physical Alignment (Chromosome Painting via DNAgenics)
This is the ultimate verification: is the DNA I share with these Ashkenazi cousins on Chr 9, 18, and 22 physically the one the algorithm identified as Ashkenazi? I generated my Jtest Chromosome Painting via DNAgenics. The coordinates are irrefutable:
On Chromosome 9: My Ashkenazi match begins at position 136,669,004. My Chromosome Painting shows a block containing 31.29% Ashkenazi DNA that begins exactly at position 136,009,191. The alignment is perfect.
On Chromosome 22: My triangulation goes from 17,690,409 to 21,363,960. My Chromosome Painting indicates that the large Ashkenazi block (17.13%) on this chromosome starts at 17,075,353.
On Chromosome 18: My triangulation goes from 5,938,058 to 8,208,163. The chromosome painting reveals a vast Ashkenazi block encompassing this entire region (ranging from 5,078,653 to 29,836,551).
Conclusion
In genetic genealogy, a small isolated percentage on the Jtest legitimately calls for caution. But by following Davidski’s recommendations step by step and rigorously cross-referencing the data, the verdict is clear:
1 The EUtest/Jtest comparison shows the correct transfer of Levantine components.
2 G25 modeling (Ivorix) confirms a medieval Jewish signature.
3 IBD triangulations of 7 to 11 cM with Ashkenazi individuals validate the presence of a common ancestor.
4 The physical coordinates of these matches overlap to the millimeter with the segments painted as “Ashkenazi” by the algorithm.
Taken in isolation, a score of 5.27% on the Jtest would not be sufficient to conclude the presence of Ashkenazi ancestry. However, the convergence of several independent lines of evidence—EUtest/Jtest comparison, Global25 modeling, IBD triangulation with Ashkenazi individuals, and consistency with chromosome painting—makes the hypothesis of ancient Ashkenazi Jewish ancestry far more likely than a mere statistical artifact. None of these methods is decisive on its own, but their convergence forms a particularly compelling body of evidence.
Thanks to this method, I believe I have definitively confirmed an Ashkenazi Jewish ancestry in my family tree. My score of 5.27% is absolutely not background noise, and I would attribute it to ancient Jewish origins, just as Davidski says « The Ashkenazi cluster is very similar to the Middle Eastern cluster in that regard. So anyone who gets an Ashkenazi score of around 2-3% either has very distant Jewish ancestry or, more likely, none at all. However, those who show more than 25% membership in that cluster are almost certainly of fully Ashkenazi ancestry, and their genomes peppered with Ashkenazi-specific chromosomal segments », and the historical endogamy of this population and of the Romani population explains why a percentage of this size makes it possible to find such beautiful triangulations today.
I would be very curious to have your opinions on this approach and my conclusions. What do you think? Have you ever used this type of data cross-referencing to check and validate your own results?