Hmm, maybe Kakashi isn't a Senju but why do you all completely deny the possibility of Kakashi being from the Senju clan? I mean, my idea isn't all that out of the realm of reality in the Naruto verse:
Anyways thx for all the comments, so far ^^Well, the assumption that Kakashi and Naruto are Senju is an old theory I made. It's pretty simple actually. Here:
The picture shows all Hokages. You see, by my understanding, Konohagakure was made up of Senju and Uchiha, only. Uchiha has left, leaves only Senjus. There are no other people there:
That's why I can't help but think that both Kakashi and Naruto are Senjus. Heritage plays a great role in Naruto.