So if they're both sealed inside Naruto, then doesn't that mean that Naruto can tap the 4rth's chakra also? Then that would mean that Naruto's got 3 chakra sources..

I dunno. I sorta follow in the Naruto is the 4rth's son belief... But I'm not closed to any new suggestions. Anbu Girl's suggestion kinda would make sense, but then it was pointed out that the third said that you only live once, therefore rebirth isn't applicable...

So, I don't know. The anime kinda STRONGLY hinted that Naruto was the son of the 4th, especially when Jiraiya apoligized to the 4th when Naruto got pushed off of the cliff. The little brother aspect didn't occur to me though....