I have generally noticed that a mama cat will begin to continually look for her kittens if they are removed before they are weaned. Although it is always good to keep at least one kitten after they have all found new homes, after at least 8 weeks of kittenhood. After they are weaned and taught to hunt, her job is done. As far as determining the genders, after a couple of weeks, you will find that the males are larger and heavier, even before they begin to sexually mature.
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