First I have to explain that I don't have a typical relationship with my older siblings. My twin and I were born after they'd left home - my brother was 17 but moved out about 6 months after we were born. Then they lived overseas or out of state and then they lived relatively close but maybe I see them a few times a year. Irrespective of that, we have a good relationship. That being said, because we don't see them so often, they haven't been made privy to Christopher's dx. However, we are having our annual Christmas dinner and DH and I are hosting. As such, I had to have *that* conversation with them today.
To be honest, I'm not sure if maybe my mom has privately shared with my sister (I haven't told her not to and I would not be upset if she had), but I felt I needed to give them a heads up as this will probably be the 1st year that his behavior would not be easily dismissed as "oh he's just that age". And I didn't want them to feel disheartened if he doesn't show the typical level of enthusiasm a 5 yr old would show at opening Christmas presents. He doesn't really get what Christmas is or Santa or any of that.
So yeah, did that - feels awkward but relieved kinda.