The ideal age for a kitten to be passed to its future pet owner is between 7 to 9 weeks, but many cat breeders release the kittens at 12 weeks because they say that the kittens are much more socialized to other kittens and are already handled by humans.
The kittens' learning process continues for as long as the litter mother remains with them. Extended time with the litter mother and sibling kittens improves socialization with and tolerance towards other cats. This is important in later life.
Basic skills developed by extended interaction with the litter mother include stalking, pouncing, and prey-kill behavior which are learned through feline activity. Kittens should be introduced to as many aspects of human life as possible to help in future socialization with their new owners.