A New York Times story says researchers studying Jefferson's Y chromosome have discovered that it belongs to a lineage rare in Europe but common in the Middle East. This has raised the possibility that the third U.S. president had a Jewish ancestor. According to the article:
"Jefferson’s Y chromosome belongs to the branch designated K2, which is quite rare. It occurs in a few men in Spain and Portugal and is most common in the Middle East and eastern Africa, being carried by about 10 percent of men in Oman and Somalia, the geneticists report in the current issue of The American Journal of Physical Anthropology."
Providing some interesting information, University of Arizona geneticist Dr. Michael Hammer said that the Jefferson Y chromosome produced four close matches in his database. One was a perfect match with a Moroccan Jew and there were also close matches with another Moroccan Jew, a Kurdish Jew and an Egyptian.
According to Hammer, he would “hazard a guess at Sephardic Jewish ancestry” for the president, albeit tentatively. Descendants of Jews expelled from Spain and Portugal in 1492 are termed Sephardic Jews.
Bennett Greenspan, president of Family Tree DNA, a DNA-testing service, said that among the 90,000 Y chromosome samples contributed to his database, K2 occurred in 2 percent of Ashkenazim, Jews of Central or Northern European origin, and 3 percent of Sephardim.
“Whether the non-Jews with K2 are descendants of Jews or come from an earlier migration into Europe is hard to say,” Mr. Greenspan said, “but my sense is that it’s separate migrations from the Middle East.”."