Thread:Kazeyo/@comment-1399043-20140828134525/@comment-1520269-20140828185444

After pondering it for a bit, I think that if an individual successfully pulled a Madara with DNA from a Uchiha or Rinnegan, they would just gain an additional doujutsu. This is due to the fact that the bonus genetic material could provide an alternative type of chakra to stimulate the eyes. Though, I'd imagine the transfer of DNA would have to be done near the eyes themselves, which sounds quite uncomfortable.

Alternatively, if a member of the Mikoto had a child with a Rinnegan user or a member of the Uchiha, then I think the results would be a bit different. For the Uchiha heritage in particular, if the child carried both the genes for Reisei and the Sharingan the resulting effect could quite interesting. Do to the fact that both doujutsu are awakened in the same manner, an emotional response generating unique chakra that transforms the eyes, it's quite possible that a single event could trigger both types of chakra at the same time. Such an event could result in an unique doujutsu possessing qualities of both eyes. Such an occurrence would likely be extremely rare and only happen if the two sources of chakra just happened to be in perfect balance. In a thousand to one cases the the user would just get one doujutsu or the other.

As for the cross between a Mikoto and a Rinnegan user, the Rinnegan would likely overshadow Reisei completely.