Turns out these BFFs have a little more than an acting habit in common. It’s been discovered that notoriously close buddies Ben Affleck and Matt Damon are related by blood. Genealogists have dug up an ancestral history that Damon and Affleck probably aren’t aware of themselves. In addition to both descending from an Ipswich, Massachusetts, bricklayer named William Knowlton Jr. (making them 10th cousins, once-removed), Affleck is also related to Princess Diana and 16 U.S. presidents, including Barack Obama, who is his 11th cousin. Damon’s lineage is only slightly less impressive—he is related to 11 former presidents. "It might be kind of one of those neat things to say at cocktail parties," said one New England genealogist. Or perfect fodder for another screenplay.