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Thomas Jefferson probably had a rare form of the Y chromosome that is more commonly seen in men originating from the Middle East and East Africa. Could Jefferson been our first Jewish president? The short answer is...maybe.
Nicholas Wade covers the story for the New York Times.
Money quote from Mr. Wade's 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.Puzzled at the lack of K2 Y chromosomes in Britain given that Jefferson’s own family traced its origin to Wales, Dr. Jobling’s group decided to scan a special population most likely to carry K2 — that of men named Jefferson.
Of 85 British Jeffersons tested, just two proved to have Y chromosomes of the K2 lineage. The paternal grandfather of one was born in Yorkshire, that of the other in the West Midlands.
Discovery of these two English members of K2 supports the idea that Thomas Jefferson’s recent paternal ancestry is from Britain. Had they not been found, Dr. Jobling’s team writes, the geographic distribution of K2 would have made the Middle East seem the most likely origin of Jefferson’s family.
The fact that K2 is common in the Middle East, however, raises the possibility that Jefferson had a Jewish ancestor, Dr. Jobling said. Jewish Y chromosomes resemble those of Middle Eastern peoples, and the Jewish Diaspora is one way Middle Eastern chromosomes entered Europe. But because so little work has been done on the rare K2 lineage, “our research raises the possibility, but doesn’t help anyone to answer it either way,� Dr. Jobling said.