The sage of six paths did have a brother after all, and he (the sage of six paths brother) must have inherited some of the juubi chakra from his mother too. If the Senju and Uchiha clan are descendants of the sage of six paths himself, me thinks the Uzumaki clan are descended from his brother??..
That would explain why they have huge chakra reserves and a high life force too?
That would explain why they have huge chakra reserves and a high life force too?