Kate and Rooney Mara
The sister actresses are NFL royalty, related to the founders and co-owners of the New York Giants and Pittsburgh Steelers. Their paternal great-grandfather was Giants founder Tim Mara, their grandfather was longtime Giants co-owner Wellington Mara and their uncle John Mara is the team's current co-owner (more on his partner Steve Tisch's Hollywood connections later). Dad Chris Mara, meanwhile, is senior vp player personnel for the G-Men. Their maternal great-grandfather Art Rooney Sr. founded the Steelers, his son Dan Rooney is chairman of the Pittsburgh team and Dan's son Art Rooney is president and co-owner of the Steelers.