Board Thread:Naruto Discussions/@comment-31844061-20200316234551/@comment-25122992-20200317001050

You're missing the main point. It's not about blood, but about merging literally the chakras of Indra and Asura. In other words, you need the original chakra of Indra and Asura (which their reincarnations have) to recreate the Rinnegan. Any random descendants of theirs won't suffice. Yes, Asura can reincarnate as an Uzumaki (Naruto is the prime example), but blood connection doesn't matter that much, the reincarnation process does. For example, Madara managed to awaken his Rinnegan as Indra's reincarnate who got the chakra of Asura's reincarnate (Hashirama), not just as an Uchiha who got a Senju's chakra.