I thought about the fact that I had done the little genetic list for Sn parents, but realistically, if the siblings mate (not unheard of in feudal societies), bam, you're back to Mange Sharingan, PLUS the child has two heads (because of inbreeding). Talk about fucked, what would Itachi do versus TWO mange sharingans!?!

( that's a joke, no need to bring back the whole "ITACHI IB SBETTAR THAN EVERYOVNE" thread.)

-xtortout