PBS said on Wednesday that it was postponing a future season of “Finding Your Roots” after an investigation revealed that the actor Ben Affleck pressured producers into leaving out details about an ancestor of his who owned slaves.

PBS will not run the show’s third season until staffing changes are made, including hiring a fact checker, it said.

The show, which is hosted by the Harvard professor Henry Louis Gates Jr., traces family histories of celebrities and public figures, and has run for two seasons. The concern about Mr. Affleck’s relative surfaced in the WikiLeaks cache of hacked Sony emails after Mr. Gates asked a Sony executive for advice about a “megastar” who wanted to omit a detail about a slave-owning ancestor.

“We’ve never had anyone ever try to censor or edit what we found,” Mr. Gates wrote to a Sony executive, Michael Lynton, in July 2014. Mr. Gates added that this would violate PBS rules, and “once we open the door to censorship, we lose control of the brand.”