Board Thread:Theories and Speculation/@comment-995176-20141108204910/@comment-3568954-20141110062942

Byakugan means white eyes or The all seeing white eyes. so all byakugan users have white eyes. but being that they are not pure hyuga and they have blue eyes. that could mean they do not have the byakugan or that there eyes will turn white when they activate them

them not having white inactivated eyes doesn't really mean anything. because one feature off an activated byakugan is the veins in the head activate and allow them the vision just like all other dojutsu the power of the dojutsu is not active unless the user wants it to be active. you can say that only the Rinne Sharingan and Rinnegan are the only eyes that are active always but we actually do not know if thats the case. we do not know if Hagoromo could turn off his Rinnegan or Sasuke can turn off his Rinnegan in the future of if Kaguya could turn off her Rinne Sharingan or what not.

and as for the incest thing Yes it appears that the main clans in the narutoverse commit incest on some level every clan we have seen has shown that clan members tend to marry other clan members. Sasuke and itachi's parents were both uchiha members(meaning they were atleast cousins) we do not know of really any senju clan members other than Hashirama, tobirama, tsunade and nawaki, (you can count both Naruto,kushina and Mito uzumaki as senju) the only senju we know of that did not marry a direct senju clan member was hashirama but we also do not know of any other senju and we have no idea of they kept it in the clan. but as it is safe to assume that the more prestigious clans likely kept it in the clan as much as possible to keep clan secrets in the clan itself