Observed from a distance while sitting at my 5YO DS's swimming lesson last week. A Mum sitting near me was talking to her friend and also trying to entertain her DD2 (DD1 in the pool). Little girl was no older than 4 and wearing a swimsuit. It's bloody roasting at the poolside so unsurprisingly she was complaining about being hot, so she took her swimsuit off as far as her waist. Her mum immediately pulled it back up and told her off for showing her boobies. Heard her say "you must never take your top off otherwise people can see your boobies." I thought it was really OTT. My DD is now a teenager and I would never have said anything like that to her so young - AIBU?