The Perks of Being a Wallflower question

I don't think she did. I think they all assumed that he just always had a hard time dealing with his aunt's death. Especially it happening on his birthday when she went out to buy him a present. It's been a while since I read this book, but for some reason I'm remembering that his mom and aunt's childhood wasn't that great. I kind of feel like her saying nothing is more her not really knowing how to help her child. I felt that she didn't want to say or do anything that might cause him to have one of episodes because they still hadn't figured out why he was going into his depressive states, they just thought it had to do with his aunt's death. Plus, I bet she was still having times where she herself was struggling with the losing her sister.

From what I got from the book and then the movie, Charlie's family always assumed that it was his aunt's death that bothered him. Even for a long time Charlie thought that it was just her death that was bothering him. His mom only finds out about the abuse at the end.

Maybe the mother had mentioned to the psychiatrist about his aunt's behavior, thinking the depression and acting out was genetic, and the psychiatrist put the puzzle pieces together...? Just a thought. It's been a while since I've read the book too so I could be dead wrong.

Yes, in the movie the therapist tells his parents what happened at the end. I think the therapist saw some signs in Charlie's behaviour that can be associated with molesting and asked him questions to determine if it happened to him.