The prohibition against speaking and hearing loshon hora also applies to relatives.  Therefore a father is permitted to inquire about his son’s studies only if he will try to help his son.  If the questioning is merely out of curiosity, it is forbidden.  The same applies to all relatives.

Seeking information about someone is permissible only when it is for a constructive purpose.  The questioner must remember to explain that he is asking for a beneficial purpose.  ~ Guard Your Tongue