In Jewish law, if an adult man has intercourse with a forbidden relative who is more than three-years and one-day old, he is punished according to the level of the prohibited relationship but the girl is exempt. If she is less than three-years old, both are exempt. So, too, if a minor boy more than nine-years and one-day old has intercourse with a woman, she is appropriately punished but he is exempt. If he is less than nine-years old, both are exempt.

Fred Rosner (Jewish professor) Encyclopedia of Jewish Medical Ethics, 2003