Ugh, unsolicited advice is one of the most annoying things we need to get used to as parents. I hate it when it happens to me, too! Can you try and look at it from a different perspective? Wouldn't you say that it's a good thing that other people are concerned about your daughter's health? I, for one, would prefer someone to suspect an issue that I can quickly rule out than to miss on a problem. I'm sure your sister loves her niece and is well-intentioned. Working as a therapist perhaps puts her in a position that makes her feel entitled to make such observations, though she could overreact given that she's sentimentally involved. From the outside, it's nice to see others care so much. And it's great that her concerns aren't confirmed! The thing is, you can't stop her from feeling this way or from talking about it. An old saying in my country goes something like this - you can't stop the wind from blowing, the water from flowing, and the people from talking. Like Christie below said, all you can do is control how you react to it. And sometimes, looking for the bright side can make it all smoother.