Wow. Your nephew seems really unlucky. I'm curiius how it affect the rest of your family. Do they feel wronged when they are on the receiving end or are you able to be objective because you know it's an illness causing the behavior?

I think it is possible that autism runs in our family because of several generations of problems on our father's side. I don't think she has mental retardation though. We were both did well in high school and college, and she won a lot of awards and competitions. Her problem with understanding simple sentences starred mid 30s so if it is a symptom it is probably something like early dementia or untreated ADHD getting worse rather than a retardation.

The screaming and banging is a problem that seems to get worse with age. I'm a little worried since I can't force her to get diagnosed that things will get much worse. I see a lot of similarity between my sister and our biological father. They were both convinced at a young age that they were geniuses so they stopped studying and got angry when others surpassed them (her not studying or practicing music seems like ADHD).

One difference between me and my sister was if someone like a parent called me a genius, I knew it was flattery and they did not really think I was a genius. My sister took such compliments literally instead of realizing people were just being polite or supportive (which seems a like aspergers to me) and she got angry when the rest of the world failed to recognize her genius (just like our father) and give her preferentail treatment. I've also been wondering if I inherited any of our parents' mental problems and regularly check myself for symptoms. If not, I might have to give some credence to my mom's ex-boyfriend's hints that he might be my real father. But he's a creep as well.

Thanks for sharing the additional info. I think I can try to navigate my crazy family now that I believe it's a mental illness problem.