I read somewhere that when they're kittens and they bite too hard when they're nursing, the momma will make a low growl at them to let them know it's too hard.
I did the same with Luna when she was a kitten and teething. She had problems with inflammated gums so she would bite my hands really bad. I growled at her because I thought this is what the mommy cat would do - and it worked great!!

Besides, even though she has been seperated early from her mommy, she's not an agressive cat, but shy and clumsy and obviously a bit depressed. But Katz was kind of aggressive, at least when she was younger.

Kirsten