Board Thread:Theories and Speculation/@comment-1872728-20160229033316/@comment-1512913-20160301233227

I actually like this theory. Uzumaki seem much more special than Senju do, with one possible exception. Hashirama was the only Senju that stood out from the rest, having had Wood Release and ability to control Tailed Beasts, also Sage Mode, which while not unique to him, seem rare enough to be noteworthy.

While the Uzumaki had things like: long lives, accelerated healing, endurance, chakra chains.

Kaguya has white hair, Hamura also had white, but Hagoromo had red hair (from father most likely). Since Hagoromo didn't have white hair, nor did his sons Asura and Indra, it's likely that the Kaguya Clan was descended from Hamura.

Also Naruto a half-Uzumaki is an Asura incarnate, instead of a Senju.

One thing to note is that the main/branch family thing tracks back to the Otsutsuki Clan, so it's possible that Asura and Indra's children and their descendants too were sorted into main and branch families.

Quite possible that the Senju are actually descendants of Asura's second born child, thus branch family, while the Uzumaki were descended from Asura's first born chlld, thus main family.