Board Thread:Theories and Speculation/@comment-995176-20161007184843/@comment-3568954-20161009170023

you are assuming that they don't still exist. its just none of them are really that important to the overall story. for all we know tobirama could have had a bunch of kids. for all we know hashirama could have had multiple kids. and who said that tsunade's parent was the one born when mito's seal nearly broke.

on a side note. the Rinnegan can only occure when indra and ashura's chakra is merged. its not enough to simply mix uchiha and senju powers. sure mixing the two powers would bring about a more powerful shinobi. but the Rinnegan can only be brought forth by indra and ashura's powers combined. so the only method this could come about is the method that madara awoke the Rinnegan. another method would be for hashirama to have stollen madara's eyes.