Our view of autism is a limited one. We do know that there is a spectrum of autisms, we do know that each case is different in it's particulars, and we do know that there are some common characteristics. But, really, the formal knowledge is very sparse, and the carers of people with autism don't have much to go on.
If you haven't had personal experience with autism, you might be thinking of Dustin Hoffman in "Rain man" right now, or a similar popular depiction. You would be wrong. I know that my understanding of even a "well-adapted" autistic person was way off the mark. Autism is, in fact, a world completely different from our own, and our attempts at grasping it fully are doomed to fail. Naoki wrote "The Reason I Jump" when he was thirteen, and his depiction of the world of autism shatters into pieces a multitude of our common sense misconceptions. So many things we would take for granted seem to be the polar opposite of reality. This is so much the case that it is difficult to classify the book as "non-fiction". Either the book was made up by someone who is non-autistic, and is complete fiction, or we have up till now grossly underestimated and unappreciated the potential and complexity of autistic personalities.