Board Thread:Theories and Speculation/@comment-734582-20150712141917/@comment-24808887-20150712223759

My guess is that Tenseigan is result of Hamura's Byakugan being affected by Hamura's Six Paths Chakra, and thus essentially transforming it to more Rinnegan like state, since theoretically speaking Hagoromo's Rinnegan without Asura's Yang half is just Indra's Sharingan, and in by themselves both of Hagoromo's sons don't have SP chakra(it comes only if they mix it). So maybe Hamura unlike his genius Aniki was late late bloomer and taked some time for him to develop his eyes while Hagoromo did it since cradle.