Board Thread:Theories and Speculation/@comment-25025726-20161107172956/@comment-24901923-20161130001910

Another possible method of obtaining the Rinnegan would be by breeding, either through Uchiha-Senju/Uzamaki pairs generally, or the pairing of the Indra and Asuma reincarnations specifically(likely through some genetic engineering), since the reincarnations are the closest to the Sage of Six Paths' chakra type.