Modern tests indicate that President Thomas Jefferson fathered his slave Sally Hemings's youngest son. Historically, Jefferson was thought to have sired Thomas Woodson, Hemings's oldest son. But in a DNA analysis published in the British journal Nature in November 1998, Eugene Foster and his colleagues presented genetic evidence from descendants of the Jefferson and Woodson families that strongly suggests that Jefferson was not Woodson's father. By analyzing genetic variations on the Y-chromosome, which is inherited exclusively through the male line, researchers found a perfect match between Jefferson's Y- chromosome and that of a male descendant of Hemings's youngest son, Eston Hemings Jefferson. From this evidence, researchers concluded that the president fathered Hemings's youngest son, Eston, rather than Thomas.