Board Thread:Naruto: The Last Discussion/@comment-732150-20150205151208/@comment-3568954-20150210143054

Omnibender wrote: Something that has been bugging me, and that I haven't seen explained anywhere. If Hagoromo was the predecessor of shinobi on Earth, and Hamura left for the moon and was the predecessor of shinobi on the moon, how come are there Byakugan users on Earth? After Kaguya, Hamura is the earliest known Byakugan user. The movie made it clear that Hinata is a descendant of Hamura, but how did that happen? There's no indication that Hamura left descendants on Earth that could have become the Hyūga clan.

the wiki here states that before going to the moon his bloodline continued through which eventually would become the Hyūga clan and the Byakugan was also passed down to them. he then went to the moon and had more descendants but instead of being called hyuga they were still part of the Otsutsuki clan, it also says that his dependents on the moon are the branch family, it says that The branch family of his descendants and the sole survivor of the Ōtsutsuki clan, Toneri Ōtsutsuki, misinterpret his celestial decree it also appears that the byakugan is rare when mixing with other blood lines and that the only sure fire way to have it at birth is via inbreeding ie cousins mating with cousins