What is the age at which a person is no longer permitted to expose their private parts?

A message was sent by a female listener. The listener (H. Z.) from Fayyum, Egypt, says: I read that the private parts of a woman in the presence of another woman, and of a man in the presence of another man, are from the navel to the knees. What is the age at which a person is no longer permitted to expose their private parts, and likewise to see the private parts of others? May Allah reward you with good?
Answer: The private parts of a man in the presence of men are what is between the navel and the knee, and the private parts of a woman in the presence of women are what is between the navel and the knee. It is obligatory for a man to cover his private parts, and if he is in prayer, it is also obligatory for him to place something over his shoulders; because of his saying (peace and blessings be upon him): . As for the woman, she must cover her entire body in prayer, her head and her hands, meaning her forearms, and likewise her upper arms, and likewise her legs; she must cover all of it, except for the palms, where there is no blame in exposing them, though covering them is better. As for the face, she exposes it. If she has not reached puberty, there is no blame in exposing her head; her head is not considered a private part, is not a private part; because of his saying (peace and blessings be upon him): . This indicates that if she has not reached puberty, it is not required to cover her head. However, if she has reached fifteen years of age, or has menstruated, or has grown coarse hair around the private parts, or has discharged semen through wet dreams due to desire or due to touching, she has reached puberty. Then she must cover her entire body except for the face and, most likely, the palms. If she covers them, it is better. May Allah guide them all. Yes.
The presenter: May Allah reward you with good and do you good.