I guess folklore wasn't quite the word I should use. That would be urban legends I'm thinking of. They wouldn't quite become a permanent fixture in society if they choose to keep to themselves. I can't imagine too many people are eager to accept deathclaws into their towns in the first place. I disagree that they're just silliness. This point is harder to argue because it just kinda comes down to personal opinion, so I'll just leave it at that. And not absolutely everything from the FEV is supposed to go sterile. That was just super mutants going sterile and abominations having their genitals all mutilated like the rest of their bodies. Wanamingos were made by FEV I'm pretty sure, and they multiply really quickly.