Thomas Jefferson was a draftsman of the Declaration of Independence and the third U.S. president (1801-09). He was also responsible for the Louisiana Purchase.
Relationship with Sally HemingsAt home, Jefferson spent his time farming, managing his finances and making improvements to the estate. It was also at this time that Jefferson most likely had an affair with a slave named Sally Hemings, who was in fact Martha Jefferson's half-sister. Sally's mother, Betty Hemings, was a slave owned by Jefferson's father-in-law, John Wayles, who was the father of Betty's daughter Sally. While there is no definitive proof that Thomas Jefferson had children with Sally Hemings, the circumstantial evidence is all but conclusive: Jefferson was with Sally (either in France or at Monticello) nine months before the birth of all six of her children.
Furthermore, historical records corroborate the stories passed down orally through the Hemings family. Most compelling is recently produced DNA evidence showing that some male member of the Jefferson family fathered Hemings' children, and that it was not Samuel or Peter Carr, the only two of Jefferson's male relatives in the vicinity at the relevant times. It is therefore overwhelmingly likely, if not absolutely certain, that Thomas Jefferson fathered Sally Hemings' children.