My Puddy was like that since I first got her at 5 weeks old and if I dare to pet her whenever I feel like it and not when she comes to me, I'll get bitten. But she used to bite for whatever reason and whenever. A gentle tap on her nose w/the words "Be nice" or "No biting" in a soft yet firm voice always got her to stop. I didn't try to explain it; I just dealt w/it which is probably wrong but I figured cats are different just as people are. She doesn't do it much any more but every once in a while......