Jokes about their level of closeness and who's banging Jimmy Kimmel aside, it turns out the longtime pals and Oscar-winning screenwriters really are more than friends and writing partners. In fact, they're related!
According to the New England Genealogical Society, the actors are both descendants of bricklayer William Knowlton Jr., an Englishman who settled in Ipswich, Mass., around 1630.
That would make Affleck and Damon approximately 10th cousins, once removed. Affleck was born in Berkeley, Calif., but spent his formative years in Boston, where he and Damon became friends.