Board Thread:Theories and Speculation/@comment-1512913-20160709202754/@comment-26369387-20160711170214

^ Well, it's hard to say, considering that it was never actually said whetever he was born with Six Paths Senjutsu or he obtained it later.

That said, even if Hagoromo obtained Six Paths Senjutsu later, it still wouldn't stop it becoming permanent part of his body and chakra.