Talk:Ghoul/@comment-27592959-20160120174328/@comment-27204325-20160120183005

@OP I honestly don't think the hard science runs that deep here. It seems clear that ghouls close genetic relatives to humans, and for them to have the same ethnic features it seems like the divergence would have had to happen pretty early on in human civilization and spread with ordinary population dispersion. But then it doesn't really make sense that they would develop the same way. Ghoul bodies are much more resistant to weather and damage on a cellular level, so there's no reason why excess body hair or dark skin would be valuable traits.

But at the same time, the parasite or foreign body theory is iffy. If the kakuhou was a parasite, why would there be half-ghouls? You don't get half a parasitic infection, and there's no reason it would only be half-expressed. In the case of natural human/ghoul children, it's pretty clear you're combining two distinct but compatible genomes, like a lion and a tiger. Hard to breed but the offspring is stronger than either parent. In the case of artificial ghouls, that's a little weird, since you wouldn't get a Liger by sticking any of a lions organs in a tiger, and that's where the foreign body thing does make sense. But I think the answer is in the RC Cells, not the kakuhou. There's a clear cutoff where, even with a kakuhou implanted, a person is still human with ghoul abilities. So, there's something about their accumulation that will cause a human without a kakuhou to die, and a human with a kakuhou to become a ghoul.