A few months ago, I read The Barbarian Conversion, which detailed the transition of post & extra-Roman peoples from paganism to Christianity. One chapter, “Rival Monotheisms,” dealt with the challenge posed by both Islam and Judaism. The author makes the case that conversion to Judaism from Christianity was a common event during the early medieval period (ergo, the later institutionalization of anti-semitism), in large part because of the familial similarity between the two faiths.
The above book was sent to the printers late in 1999, and 6 months later, a paper was published that suggested that the male lineages of European Jews were predominantly non-European in origin (an admixture rate on the order