6 weeks??? Ouch -- that is harsh. Kitties shouldn't leave their mamas before 12 weeks is what they are saying now.
Anyway...when does the bite happen? Sometimes if you pet your cat for a long time, they will bite b/c of overstimulation. Every cat has a petting threshold. It's up to you to learn the warning signs and become accustomed to how long your cat is willing to be pet. Ears back, tail flicking turning into more of a swatting motion, skin rippling along the back are all signs that your cat's threshold is almost reached, and you should stop petting. Some cats just don't like being pet if they aren't in the mood. So if you even come at a cat with a hand, totally calm and gentle, and they aren't in the mood, they will swat and bite. If you see your cat even begin to do this, just leave it alone.
If it's not during petting that your cat is biting you, your cat might have gotten used to playing with your hands. If your cat bites you, you should go limp and say "ouch!" Never tug or pull or swat your cat away -- they will think you are playing and therefore the behavior is reinforced. When your cat bites, after you go limp and cry out, stop playing with it immediately. This lets them know that the behavior is not fun and not welcome.
It's possible that not everyone in the house is treating the cat with respect, more like a plaything that should be willing to be pet and held and played with by whoever wants to at the time. I've seen this a LOT with friends in college who have a bunch of people living in an apartment. If the cat is hiding, let it hide. Don't yank it out to play, of course it will bite then. If the cat is sleeping, let it sleep. Same thing. Respect the cat's space as well as the cat's independence, and make sure everyone in the house knows this. The cat just might not like all the different people that are around and wanting to touch it all day.
