Thomas Jefferson's lineage?

Everytime I try to look up Thomas Jefferson's lineage I come up with the slave scandal and his POTENTIAL lineage, but I'm looking for the definite lineage, the one he had with his wife Martha. I know they had few kids and his daughter, Martha Jefferson, had a son named Thomas Jefferson Randolph who joined the confederates, but I'm looking for something past his grandchildren. I can't believe that a mind as brilliant and extroadinary as his would go to waste by his line eventually dying out. Please help me. I want to know who his surviving ancestors are, or how far you can trace them. Thank you so much!