[Titus Quinctius Cincinnatus]

Arthur Koestler thought that an Asiatic Tribe called the Khazars converted to Judaism in the 10th century or so and that Ashkenazi Jews are descendant from them. He put forward the theory in the hopes that it would deflect accusations from Deicide from contemporary Jews who would have no connection to Roman era JEws. Today the theory is favored by Neo Nazis and Muslims as it also invalidates Jewish claims to the Holy Land.

The Kagan of the Khazars, and the aristocracy, converted to Judaism, but it's unlikely that the bulk of the common people did.

[wideawake]

A genetic study out of Canada, perhaps out of McGill, a few years back demonstrated that Jews whose families are Kohanim actually do share an allele that is traceable back to a common ancestor in the region of ancient Israel - pretty much dynamiting the old Khazar theory.

The Jews are distinctive in that their matrilineal identification enabled converts to integrate into the gene pool (unlike other closed religious groups like the more recent Druze, Yezidis and the Zoroastrians), in that they were still pretty dedicated to intermarriage up until the 1800s, and in that within the Jewish population there is Kohanim/Levite population that also practiced internal intermarriage.

Plus, it's such a large sample.

[Verginius Rufus]

So are Jews today with the surname Kagan descended from the Khazars, and the rest from the ancient Israelites?