From what i understand, it is genetic. That's why they used it for suicide bcs mingling with human will kill them.
Hmm but from the chapter it seems like since its so taboo, its no genetics but they actually hunt down and kill their own who do it.
No, it is genetic. They do kill their own if they find out about it tho. They will kill the one who mingling with human before they can get pregnant, bcs child between their clan and a normal human is a heresy. But, the genetic one will make them died if they giving birth to normal human child.
I thought the dieing after mingling with outsiders thing was genetic, but that seems to not be the case,,, dang thats terrible