Re: At what age is it not appropriate?
My kids will still wander in when I am changing (oldest is dd 8) and they don't think anything of it. no one is bothered by it yet so it hasn't been an issue-once anyone is uncomfortable though then I think we need to adjust the rules. Our kids don't have a lot of modesty yet though, at least not around us (more so others)
I kind of disagree with the notion than when they start asking questions or pointing out differences they can no longer see you naked-sends the wrong message to me. Kind of like telling them the questions were wrong or it is not okay to talk about these things. Around age 2 or 3 our kids all noticed differences and asked about it-we answered them honestly and that was the end of that-no more questions. I don't wander around without clothes on but if they happen to barge in the room when I am changing I don't scream and duck for cover.
DD 9, DS 8, DD 3,DS 2, and DD 7 mos