A father is obligated to teach his son Torah. One who was not taught by his father must teach himself (Shulĥan Arukh, Yoreh De’a 1). A mother is not obligated to teach her son Torah, as only those who are commanded to study are commanded to teach others. Nevertheless, a woman who studies Torah receives a reward, like those who fulfill a mitzva that they are not obligated to perform (Rema on Shulĥan Arukh, Yoreh De’a 246:6).