Reddit reviews Unstrange Minds: Remapping the World of Autism

Unstrange Minds is good to the science and social aspects of Autism. It will really help in understanding the history behind how autism is seen and some of the hysteria.

You should definitely get a second opinion. From what I understand RAD is often diagnosed in place of autism. For whatever reason it was thought to be more socially acceptable to blame the mom for a kids social delays (google "refrigerator moms") than to accept that there might be something intrinsic about the kid that we don't understand. The book Unstrange Minds has a whole chapter on the history of blaming moms for autism. You should definitely look into the signs and symptoms of ASD. Plus, getting a diagnosis may open up treatment options for your kid that are unavailable under RAD.

I'm afraid I don't have any specific advice for how to help your family. There's a book called Unstrange Minds which looks at how autism is perceived and understood in a number of different countries, including countries where having a disabled child is considered shameful for the family. The author writes about how, in both India and South Korea, there are parents who have sought acceptance and treatment for their child despite cultural forces. If you haven't read it, I wonder if it might give you ideas about how to move forward.