Board Thread:Naruto Discussions/@comment-24837927-20140421121126/@comment-26302001-20140425144959

Rinnegan is a Kekkei Genkei says Kishi and his Databook 3. If Hashirama had 2 sons, and their descendants DNA/Chakra was connected together like Madara did, then they would gain Wood Release just like Madara gained Rinnegan, that doesn't mean Wood Release isn't Kekkei Genkei now does it?