Board Thread:Theories and Speculation/@comment-45444155-20200826144850/@comment-32685487-20200826213116

Normally it requires an implant of the foreign DNA, and your body has to accept the implant but as far as Tailed Beast flesh, all you have to do is eat it and hope your body has the genetics for it to accept it too(be a descendant of the Sage himself). This also explains why Guy doesn't just get a Hashirama clone leg.. his body probably wouldn't accept the leg. Also it has to be an actual implant, not just some piece you stuck ONTO your body like Naruto and Danzo had done.