My dad (in his 70s) asked if my sister's DH as "babysitting" their child. I said, in what I thought was just a chatty way, no because it's parenting. He said "what?" and I replied that it's something people often say about dads, not mums. He said that he would have said it about my sister as well. I don't think that's true but didn't say anything else as I could tell he was annoyed. My dad stormed off and sulked for the rest of the evening. I don't know how the evening was ruined. I really didn't mean to cause an issue. I thought I we were just chatting. AIBU?