Lot's of cat's bite because the owner's have used their hand's in play when they were kittens & so it end's up being a bad habbit they cannot shake.
Also it's a way they say enough is enough, I want to be left alone now.
They cannot talk & say ok tired of this game now, so don't over play.... Wach for sign's, tail swishing, ears back. Hopefully folk would stop before they get to this point.