Hollywood star explored his family's past on PBS documentary Finding Your Roots but viewers were not told one ancestor owned slaves Leaked Sony emails reveal how Henry Louis Gates Jr told a friend Affleck was trying to 'censor' documentary - a breach of PBS rules Gates asked his friend Sony boss Michael Lynton for advice and was told by Hollywood chief: 'I would take it out if no one knows' Instead show was about prominent liberal Affleck's Freedom Rider mother and distant ancestor who was mystic in civil war Gates claimed today that the slave-owning ancestor was not 'interesting' Latest embarrassing disclosure from leaked Sony emails posted by Wikileaks raises questions over PBS's integrity and for Gates, a Harvard professor