I'm not sure this is very helpful, but I think I'd try to ask questions about what _they_ think happened and whether or not it was OK. E.g. I noticed you said X to your brother. How do you think he felt about that? How would you feel in that situation?

I feel like we have the opposite problem at our house - DS7 can't stand people saying anything nice about him/his work. He always contradicts you and says "No it was bad".