Board Thread:Theories and Speculation/@comment-5413572-20150114180437/@comment-1512913-20150210155344

Except the lore says otherwise. Merging the chakras of both Asura and Indra incarnates restores Hagoromo's chakra, which by your logic shouldn't be possible because evolution occurs and the incarnates simply by having chakra and genes from their actual parents would make the merged chakra not 100% as Hagoromo's but different. Not to mention the databook says that Kaguya's chakra literary dispersed into Hagoromo and Hamura, so what they have so she did. If Asura and Indra's chakras make up Hagoromo's, Hagoromo and Hamura's chakras make up Kaguya's. Madara with Hagoromo's chakra could still use Sharingan, so logically Kaguya should have Rinnegan and Tenseigan since her children's chakras are but halves of hers.

For other kekkei genkai evolving, not sure about that, since the databook says that the known kekkei genkai are fragments of Kaguya's power and Orochimaru and Kabuto's quest to retrace back to Hagoromo's power by taking people's cells support that. If the current chakra/genes were evolved, retracing wouldn't be possible since the result would be different.