Board Thread:Theories and Speculation/@comment-5060540-20200422213933/@comment-32685487-20200522070149

All BZ said was that Nagato was the perfect host for the Rinnegan from what I remember, I will have to go check the chapters again tomorrow, BZ also pointed out Nagato's Senju lineage(stating this was why even with Rinnegan only Nagato and Madara could summon the Gedo Mazo) and Obito pointed out his Uzumaki lineage. I think Nagato just happens to be Uzumaki and Senju(like Tsunade and Nawaki) and a natural chakra monster and that makes him a perfect host for the Rinnegan.