My MIL has asked prying questions and made inappropriate comments numerous times in the past. This time, she asked her 13yo granddaughter/my niece if she had started wearing a bra, and then shared that information with other family members (me, my DH, and my DD). I was gobsmacked when I heard about it but MIL thinks it's her right to ask anything because she is a part of the family. I think she totally crossed a boundary - especially asking such a personal question to someone at a sensitive age. Am I too sensitive and overreacting? For your reference, MIL wasn't going to buy a bra for her DGD. AIBU?