Well, could Chakra.... for example Nature Chakra affect DNA? Look at Juugo, and Look at Naruto when goes Toad Sage Mode... With that being said... Could Nature Chakra from the Juubi, Senju and Uchiha DNA + Chakra From all three sides "Because Madara can use Wood Release Now"... be enough to awaken the Rinnegan? I could see how the Juubi's Chakra affects Madara's DNA... Like Kurama Chakra affected Naruto's DNA "The Whiskers"... and the Senju DNA Accelerated the awakening? Juubi's Chakra from the Fruit affected the Sage and gave him the Rinnegan. Nevermind it wouldn't make sense... Madara awaken the Rinnegan, and summon the Juubi's Shell from the moon.... Madara awakening the Rinnegan is still a little bit fishy.