Kirk Douglas, Michael Douglas and Cameron Douglas

The Douglas family is considered Hollywood royalty, with Kirk having three Oscar nominations and his son Michael having won two (one for jointly producing One Flew Over the Cuckoo's Nest and one for acting in Wall Street). But three generations of the Douglas clan took to the screen in the dramedy It Runs in the Family (2003), which starred Kirk, Michael, and Michael's son Cameron (whose mother is Diandra Douglas). Kirk's wife (and Michael's mother) Diana Douglas also acted in the film, which was only Cameron's second movie.