The Simpsons have the most extensive fictional family tree I've ever seen. Published in The Simpsons Uncensored Family Album, it reveals that Homer's 3rd-great-grandfather's sister married the brother of Mr. Burns' 2nd-great-grandmother, and that Lisa Simpson really does have Native American ancestors (though perhaps not of the Hitachi tribe). (Marge's ever-so-French ancestry—summarized here—also appears in the book.)
