A recurring observation in population genetics is that Ashkenazi Jews often cluster with Southern Italians and Sicilians in PCA plots and G25 analyses. This similarity, however, does not imply direct kinship, but rather parallel demographic trajectories that produced convergent ancestry compositions.

Shared Mediterranean–Levantine Foundations

Both Ashkenazi Jews and Southern Italians share high proportions of Southern European and Levantine ancestry.

  • For Ashkenazi Jews, the Levantine ancestry reflects their deep Middle Eastern origin, with continuity from ancient Jewish populations and subsequent integration with local Italians during the Roman Empire. Ancient DNA studies show that Jewish communities in Roman Italy retained Near Eastern ancestry while admixing with locals. In addition, Ashkenazi Jews sometimes display minor Siberian, Central Asian, or East Asian signals, usually reflecting admixture acquired along the Silk Road rather than direct East Asian forebears. It is also worth noting that the “West Euro” component mainly applies to Western European Ashkenazim (those with roots in France, Germany, or the Low Countries), while Eastern European Ashkenazim tend to show stronger Slavic or Balkan-related influences.

  • For Southern Italians and Sicilians, the Levantine signal is tied to Phoenician colonization, the Roman–Byzantine presence, and later Mediterranean exchanges. Genome-wide studies confirm significant Levantine admixture in Sicily and southern Italy from the Iron Age through the medieval period.

Thus, both populations converge genetically because of similar ratios of Southern European and Middle Eastern input.

Distinguishing Features of Ashkenazi Jews

Despite the clustering, Ashkenazi Jews are distinguishable by additional admixture layers absent in Southern Italians:

  • Northeastern European ancestry (~5–10%): Likely linked to conversions and gene flow from Slavic/Baltic groups during the medieval diaspora.

  • Western European ancestry (~5–7%): Medieval German and French Jewish communities contributed to the Ashkenazi gene pool.

  • Trace East Asian/Siberian signal (~1–2%): A small but detectable component.

Southern Italians, in contrast, lack these northern and eastern inputs, their profile remaining almost entirely Southern European + Levantine.

Approximate Genetic Composition (G25-based)

  • Ashkenazi Jews

    • Southern European / Italian: ~45–50%
    • Levantine: ~40–50%
    • Northeastern European (Slavic/Baltic): ~5–10%
    • Western European (German/French): ~5–7%
    • East Asian/Siberian trace: ~1–2%

  • Southern Italians and Sicilians

    • Southern European: ~55–65%
    • Levantine: ~30–40%
    • Negligible northern/eastern input

This composition explains why the two groups overlap so closely in PCA plots, yet can still be separated in supervised admixture models.

Visualization

The bar chart below illustrates these contrasts, showing the shared Mediterranean base but also the extra northern and eastern elements unique to Ashkenazi Jews:

Admixture bar chart

Conclusion

The Ashkenazi–Southern Italian genetic similarity is a case of convergent demographic history rather than recent shared ancestry. Both populations absorbed substantial Levantine and Southern European ancestry, but Ashkenazi Jews further incorporated Western European, Northeastern European, and minor East Eurasian signals. These additional layers, supported by both modern G25 coordinates and ancient DNA, make Ashkenazi Jews genetically distinguishable despite clustering with Southern Italians in unsupervised analyses.

References

For those interested in further analysis or visualization, here are the G25 coordinates of the sample:

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Ashkenazi_Austria,0.095611,0.137096,-0.011502,-0.047481,0.010925,-0.014781,-0.00235,-0.002884,0.009715,0.014214,0.002923,-0.001649,-0.000595,0.001101,-0.00475,0.001525,-0.008605,6.3e-05,-0.001446,-0.002814,-0.002184,-0.003091,-0.001417,0.001205,-0.000898
Ashkenazi_Belarussia,0.101915,0.133972,-0.00734,-0.03958,0.010771,-0.014459,-0.001012,-0.00103,0.005727,0.014621,0.002448,-0.000369,0.00231,-0.001461,-0.002944,0.002795,0.001815,-0.000341,0.001489,-0.00126,-0.003859,-0.00077,0.00274,0.001566,-0.000295
Ashkenazi_France,0.095611,0.143697,-0.015132,-0.051357,0.009309,-0.019487,-0.002526,-0.002048,0.008564,0.019545,0.003776,-0.000937,0.002509,-0.002305,-0.003647,0.003182,0.000896,-0.002265,-0.002137,-0.005393,-0.000889,-0.00289,0.00037,0.002591,0.001602
Ashkenazi_Germany,0.097319,0.142377,-0.014406,-0.049936,0.010925,-0.018769,-0.001974,-0.001754,0.009858,0.018843,0.003962,-0.001124,0.002512,-0.00267,-0.005049,0.003089,0.002203,-0.001698,-0.000779,-0.001126,-0.003344,-0.002696,0.000875,0.001386,0.000814
Ashkenazi_Latvia,0.097319,0.135065,-0.016216,-0.043767,0.00677,-0.015757,-0.00329,-0.004038,0.004909,0.013485,0.001949,0.001723,0.006467,0.002133,-0.006922,-0.004177,-0.006128,-0.001077,-0.000754,-0.005753,-0.003931,-0.002782,0.001849,0.003012,0.003413
Ashkenazi_Lithuania,0.099854,0.132757,-0.009222,-0.040375,0.009484,-0.014147,-0.000556,-0.001175,0.006061,0.013701,0.00155,-0.001853,0.002568,0.000625,-0.004442,0.003459,0.0016,0.000161,0.000446,-0.003172,-0.003256,-0.00335,0.002924,0.002443,-0.001056
Ashkenazi_Poland,0.100117,0.136843,-0.007338,-0.043,0.009797,-0.015409,-0.000881,-0.000894,0.008198,0.014275,0.001164,-0.000593,0.00288,0.000166,-0.004145,-0.001674,-0.003765,3.2e-05,-0.000807,-0.004064,-0.002678,-0.002272,0.001689,0.002169,0.001527
Ashkenazi_Romania,0.102441,0.137096,-0.006222,-0.042798,0.010002,-0.015478,-0.00376,-0.000808,0.006238,0.015034,0.004141,0.002473,-0.000446,-0.000413,-0.001968,-0.001326,-0.003651,0.000697,-0.000817,-0.008316,-0.003806,-0.003277,0.001725,0.006868,0.000359
Ashkenazi_Russia,0.101189,0.131511,-0.006449,-0.038276,0.010371,-0.014335,-0.001951,-0.000185,0.006545,0.01405,0.00112,3e-04,0.002141,0.00033,-0.005035,-0.000265,-0.001213,-0.00057,-0.002137,-0.003126,-0.003569,-0.002955,0.000629,0.004579,-0.001221
Ashkenazi_Ukraine,0.099424,0.135116,-0.005506,-0.040117,0.012048,-0.014265,-0.001093,0.000115,0.007772,0.012939,0.000804,0.000112,0.002416,0.000523,-0.00283,-0.00183,-0.004322,-1.9e-05,0.001276,-0.004677,-0.003126,-0.002591,0.00077,0.002103,0.001006
Italian_Abruzzo,0.112685,0.148801,-0.000675,-0.034765,0.016116,-0.01255,0.000779,-0.002283,0.003789,0.020813,0.000513,0.003668,-0.005633,-0.003904,-0.00615,-0.001466,0.00186,0.000267,0.003361,-0.003693,-0.003809,0.001334,0.000889,0.001706,-0.000964
Italian_Apulia,0.110712,0.148267,-0.003771,-0.040138,0.015839,-0.015116,-0.000956,-0.001615,0.002795,0.02069,-0.000227,0.003877,-0.006472,0.001193,-0.008107,-0.003898,0.001669,6e-04,0.002749,-0.005152,-0.00381,0.001962,0.001758,0.001438,-0.000567
Italian_Calabria,0.103437,0.14814,-0.010324,-0.046997,0.012618,-0.015025,-0.002438,-0.001586,0.004448,0.021231,0.002213,0.002997,-0.004887,-0.001737,-0.006549,-0.002784,0.005802,0.000728,0.002938,-0.005362,-0.002605,-0.000325,0.000339,1.5e-05,-0.002425
Italian_Campania,0.108263,0.148384,-0.008529,-0.043456,0.014038,-0.016154,-0.000777,-0.002201,0.004507,0.0221,0.000968,0.002265,-0.00498,-0.00144,-0.006259,-0.000806,0.002332,0,0.002814,-0.003728,-0.003964,0.001907,0.000256,0.002104,0.000189
Sicilian_East,0.1032,0.146574,-0.007291,-0.041129,0.017849,-0.015339,-0.001958,7.7e-05,0.007567,0.021322,0.007307,0.003897,-0.006145,0.003119,-0.005926,-0.006497,-0.002868,-0.00114,0.004483,-0.003877,-4.2e-05,0.002679,-0.00189,0.002289,0.000399
Sicilian_West,0.100164,0.145559,-0.000377,-0.03553,0.019388,-0.009854,-0.000627,0.000538,0.013362,0.022293,0.00341,0.003097,-0.00223,0.001881,-0.002262,-0.003182,-0.001869,-4.2e-05,-0.00088,-0.006128,0.000832,0.000824,-0.003204,-0.003494,0.000239