There are different kinds of autism. Low
functioning, middle functioning and
high functioning.
Some of the lower functioning people with autism have the intelligence of a baby, in which they can only scream, grab at your shirt, drool, and do other baby type stuff.
However, there are people that are autistic that are very smart, such as Bill Gates.
To people that
generalize autistic kids as retarded, be quiet, because you're probably using Windows.