A Falsification Test of Ashkenazi Modeling: Autosomal Evidence from Italkim Jews

A falsification test of Ashkenazi ancestry modeling using Italkim Jews demonstrates that Ashkenazi populations trace their primary ancestry to Greco-Roman groups inhabiting southern Italy, Sicily, and the regions historically known as Magna Graecia. These populations contributed the vast majority of Ashkenazi autosomal DNA, inherited from both maternal and paternal lines over millennia. Online forums, including Quora and Reddit, have repeatedly treated the genetics research of Dr. Harry Ostrer and colleagues as dogma, claiming that Ashkenazi Jews have overwhelmingly Levantine paternal ancestry and substantial European maternal ancestry. These discussions often dismiss PCA and FST results as methodological artifacts and instruct readers to ignore them, implying that the observed Ashkenazi clustering with southern Italians is an error rather than a reflection of historical ancestry. This interpretation is incorrect: Italkim Jews serve as a direct falsification test, with overwhelmingly ancestral ties to Ashkenazim and continuous residence in the southern Italian peninsula for approximately 2,400 years. Autosomal evidence from Italkim Jews demonstrates that southern Italian and Magna Graecia ancestry forms the core of Ashkenazi populations, directly contradicting the forum narrative and reinforcing the historical continuity of these Jewish communities in the central Mediterranean.

Italkim Jews as an Autosomal Falsification Test

Italkim Jews of southern Italy provide a robust autosomal falsification test for claims that Ashkenazim cluster with southern Italians due to maternal European ancestry. Unlike Ashkenazim, Italkim have never migrated to the Rhineland, Central Europe, or Slavic regions. They have continuously lived in southern Italy since the era of Magna Graecia and Roman times. These communities were established during Greek colonization and survived through successive Roman, Byzantine, and later medieval administrations, preserving their unique genetic heritage. Their autosomal DNA, inherited from both parents, confirms that both maternal and paternal contributions are fully represented, allowing for a reliable falsification test against claims of artifact-driven clustering.

Southern Italian PCA and FST clustering is not an artifact, and principal component analysis (PCA) and FST measurements provide independent lines of evidence that capture overall genetic similarity, reinforcing that Ashkenazi clustering with southern Italians is historically grounded rather than a statistical anomaly.

PCA Plot: Southern Italian and Magna Graecia Greek Affinities

The PCA plot demonstrates autosomal continuity from Magna Graecia Greeks and ancient Romans to Italkim Jews and southern Italian populations. This directly contradicts forum claims that Ashkenazim cluster with southern Italians solely due to maternal European ancestry.

G25 Similarity Map: Autosomal Clustering Patterns

The G25 similarity map shows that Italkim Jews cluster most closely with Sicilians, mainland Italians, Maltese, and Aegean Greek populations, reflecting their ancestry from Magna Graecia Greeks and ancient Romans. These populations settled southern Italy during the Greek colonization period and persisted through Roman rule, creating a continuous genetic record that is directly relevant to Ashkenazi ancestry. The clustering in the G25 map demonstrates that the observed genetic affinities are not artifacts caused by maternal European admixture, as some forum discussions claim, but rather reflect real historical connections.

The G25 findings align with the PCA results, confirming that autosomal data consistently place Italkim Jews and Ashkenazim within the southern Italian and Aegean Greek genetic space. By including reference populations from southern Italy, Sicily, Malta, and the Aegean, these analyses avoid distortions that arise when using Northern Italian, Tuscan, or Sardinian proxies. The results provide strong evidence that Ashkenazi clustering with these populations reflects genuine historical ancestry, captures both maternal and paternal contributions over millennia, and highlights the continuity of Greco-Roman genetic influence in Ashkenazi Jews. All of the tools used in this analysis, from FST to PCA, can be found on ExploreYourDNA, and the full results are documented in the author's study available on Preprints.org.

FST Analysis: Genetic Proximity of Italkim Jews

The following FST table shows the 30 populations closest to Italkim Jews. These data further confirm their genetic affinity with southern Italian and Greek populations.

Conclusion

The perception in genetic studies that Ashkenazi clustering with southern Italians is an artifact arises from repeatedly defining "Italy" as Tuscany, Northern Italy, or Sardinia and ignoring the only continuously present Italian Jewish ethnoreligious group, the Italkim Jews of southern Italy. Autosomal evidence from Italkim Jews demonstrates that Ashkenazi clustering is real, robust, and historically grounded. Their autosomal DNA, reflecting over 2,400 years of continuous residence in southern Italy and deep ancestral ties to Magna Graecia Greeks and ancient Romans, directly contradicts forum claims dismissing PCA and FST placement as an artifact. These data further show that northern or central European ancestry does not account for this clustering pattern and that Ashkenazi ancestry is firmly rooted in southern Italian and Greco-Roman populations overall, confirming historical continuity and genetic authenticity.