According to leaked Sony emails, Ben Affleck asked PBS producers not to reveal one of his ancestors was a slave-owner.

Ben Affleck, 42, was taking part in PBS’ Finding Your Roots series, where experts research a celebrity’s family history, when the discovery was made.

The public television says in a statement that they didn’t censor the slave-owner details.

It is “very common” to find slave-owning ancestors during research, the show’s host says.

“For any guest, we always find far more stories about ancestors on their family trees than we ever possibly could use,” Prof. Henry Louis Gates says in a statement sent to The Associated Press.

Photo PBS

Prof. Henry Louis Gates says both film director Ken Burns and journalist Anderson Cooper also found out while making Finding Your Roots that relatives of theirs had owned slaves.

The details of Ben Affleck’s slave-owning family member were not included when his episode of Finding Your Roots was broadcast.

“In the case of Mr. Affleck – we focused on what we felt were the most interesting aspects of his ancestry – including a Revolutionary War ancestor, a third great-grandfather who was an occult enthusiast and his mother who marched for Civil Rights during the Freedom Summer of 1964,” says Prof. Henry Louis Gates in a statement on the PBS website.

Earlier this year, Ben Affleck received a People’s Choice award for his humanitarian work in the Democratic Republic of Congo.

The email chain between Prof. Henry Louis Gates and Sony Pictures co-chairman and chief executive Michael Lynton was one of many thousands of emails and documents from last year’s Sony hack that WikiLeaks put into a searchable online archive on April 16.

“Here’s my dilemma: 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,” Henry Louis Gates wrote on July 22, 2014.

“Now, four or five of our guests this season descend from slave owners, including Ken Burns. We’ve never had anyone ever try to censor or edit what we found. He’s a megastar. What do we do?”

Michael Lynton replies the same day, saying: “I would take it out if no one knows, but if it gets out that you are editing the material based on this kind of sensitivity then it gets tricky. Again, all things being equal I would definitely take it out.”

After further exchanges Henry Louis Gates and Michael Lynton seem to agree that censorship is a bad idea.

“It would embarrass him and compromise our integrity. I think he is getting very bad advice,” Henry Louis Gates writes.

“Once we open the door to censorship, we lose control of the brand.”

Ben Affleck is never referred to by name in the emails – instead he is called “megastar” or “Batman”. At the time of the exchange Ben Affleck was filming Batman v Superman: Dawn of Justice.