Board Thread:Naruto Discussions/@comment-3232093-20140617193601/@comment-23887466-20140818183212

@Legendary: its stated that Hagoromo awakened the Rinnegan, he wasn't born with it.

In any case, Black Zetsu, must have build his theory on someone. By theory, I mean the evolution of the Sharingan to Rinnegan, afterall he put all his theory in the Uchiha Tablet so that one of them will try to do it, which Madara did. That someone must be Hagoromo, because Black Zetsu stated that Both Hagoromo and Madara are the only people who awakened the Rinnegan.