If Hillary Clinton is a ninth cousin (twice removed) to Angelina Jolie, and Barack Obama is a ninth cousin to Brad Pitt, maybe the race for the Democratic nomination is just an ancient lovers’ quarrel, looping endlessly, one generation to the next.

Henry Louis Gates Jr. may never sleep.

Gates, 57, is a Harvard professor as well as an author and editor of a shelf-load of books. He’s also the host of African American Lives, a PBS series on genealogy that begins its second season next week.