valid point but think of the similarities of the gobi and other bijuu when they become sealed within a host. Naruto for example has gotten from kyubi, stronger chakra, different forms of the bijuu/host (chakra cloak and bijuu form). When we see sasuke use moves like amaterasu and susano it just reminds me to much of a jinchuriki's powers, amaterasu uses black flames, why? the taild beast bomb uses black (and white) chakra and i think amaterasu utilizes the black chakra while maybe tsukuyomi uses the white chakra since tsukuyomi isnt a normal genjutsu and susano just like the jinchuriki's can alter its form more than once. To me it just seems the sharingan is a trait from the gobi given to the sage just like all the other bijuu give traits to the jinchuriki. Izanagi is also another sharingan move which the sage was known to use, he used it to make the other bijuu so that means he already had the gobi within him when he did so we can assume he used the powers of the gobi to make the other bijuu since the gobi had sharingan therefore izanagi. If your wondering about my point when the jinchuriki go to bijuu form and they look like there beast it doesnt appear that way with susano but we also have to remember that the bijuu were all made from only the gobi's chakra while the actuall body of the gobi was sealed in the moon along with the sage. In my opinion the rinnegan and the sharingan have completley different powers and are not related in gene form, however the ms sharingan raises some questions because the exact way it is obtained is still out there. itachi said kill your friend however how do you explain kakashi and sasuke? so it cant be that simple???????