Two men in Britain have been shown to belong to the same rare haplogroup as Thomas Jefferson.
This discovery of K2 in Britain scotches any suggestion that Jefferson - who was US president between 1801 and 1809 - must have had recent paternal ancestors from the Middle East.
Jefferson's Y chromosome was most similar to that of a man from Egypt. But genetic relationships between different K2s are poorly understood, and this may have little significance.
Instead, say the researchers, their study makes Jefferson's claim to be of Welsh extraction much more plausible. [Link]