Founding father Thomas Jefferson was a lot of things: red-haired, bookish, founder of the University of Virginia, revolutionary wunderkind, patron saint of the Democratic Party, architect, and author of the first draft of the Declaration of Independence with it's all-too-often-quoted boilerplate of "all men created equal" and their vaunted "pursuit of Happiness." Thomas Jefferson is pretty complicated. Of course all the American political saints are complicated. Franklin seems more Voltaire than Washington--like some 18th century philosophe stumbled onto the set of a war movie and did his best not to smirk while delivering his lines. Washington stands a strange cipher of virtue: the only thing you can be certain about is that he was an important, powerful man, and knew himself to be as much. Hamilton is equal parts martyr and New York City capitalist. If he'd be alive today he'd be reviled like Rahm Emanuel or envied like an Uber engineer. But despite all that, Jefferson has perhaps the most fraught historical legacy.
This is because of his relationship with Sally Hemings, his slave, the mother of his children, his wife's half sister, a relationship that was for a long time controversial, disputed, denigrated, a relationship which brings to light a lot of the complexities of America's tortured history of racial discrimination. His wife, Martha, died at 33 and made Jefferson promise not to marry again because she could not bear to have another woman raise her children. But Jefferson had also inherited more than a hundred slaves from his father-in-law. Amongst those slaves was Martha's half-sister, Sally Hemings.
Hemings and Jefferson had six children. Four survived. They were 7/8s European, and were freed by Jefferson on reaching adulthood. Three of them went on to pass as white. Jefferson's son Eston Hemings moved to Madison, Wisconsin, changed his named to Eston Jefferson and his children and grandchildren entered the white community, claiming some vague relation to some side of the Jefferson family tree. Madison Hemings, on the other hand, remained black, and his descendants considered themselves black. One set of brothers and sisters branched to live out their lives on either side of America's brutal color line.
For more, check out BackStory's history of Racial Passing in America.