Animals dont just turn 'feral' overnight, and because one of your ferrets is a biter dosn't mean it's behavior will influence the rest. Now i'll admit, I've come damn close to putting a .22 pellet into my albino jill, because she was a hell of a biter, but after 2 weeks of extra handling and showing her who is boss, she was a totally different animal, and she is a good worker.