Ben Affleck allegedly wanted details of his slave-owning ancestors to be cut out of a documentary.

The 42-year-old actor, who's set to star as Batman, is reported to have persuaded the producers of 'Finding Your Roots' to ignore details of how his ancestors were slave owners, despite the move representing a breach of PBS editorial rules.

A leaked email from Sony chief executive Michael Lynton to the show's host Henry Louis Gates Jr reads: ''I would take it out if no one knows.''

Gates replied by saying that ''once we open the door to censorship, we lose control of the brand'', but it appears that's what subsequently happened.

Later, he added: ''Confidentially, for the first time, one of our guests has asked us to edit out something about one of his ancestors--the fact that he owned slaves.

''Now, four or five of our guests this season descend from slave owners, including [documentary filmmaker] Ken Burns.

''We've never had anyone ever try to censor or edit what we found. He's a megastar. What do we do?''

The show ultimately didn't include the information regarding Affleck's slave-owning ancestors, but did reveal he is distantly related to his long-time friend Matt Damon.