You must be registered for see images
What Kakashi said here can be half true. But what if the relation he spoke about is exact opposite to the real thing? I mean what if Hyuuga's Byakugan's origin lie with the Uchiha's Sharingan?
You know that the children of the Hyuugas has Byakugan from their birth, but the Uchihas had a normal eye. So SO6P being a Hyuuga doesn't fit at all.
I can't say which clan does the SO6P belong to, but his elder son got the rinnegan (directly).
From this, I can say that the Uchihas and the Hyuugas origins from the Elder Son. Don't go with the pattern in their eyes. Instead they both possess mostly same ability. But the Hyuugas got much of the advantage in their initial stage itself and are limited to it whereas the Uchihas had to achieve the strongest Sharingan (EMS). And to achieve rinnegan, they had to become one with the Younger brother's blood (maybe Senju + Uzumaki/Namikaze) since they both are the sons of same father.
But the most important thing is that among all these branched clans, the Senjus and the Uchihas are the main clans related to the Younger and the Elder son of the SO6P directly.
What's your opinion?