Autism is not mental retardation. Some autistic people may be very intelligent there is a lot of evidence that Albert Einstein may have been autistic. Some autistic people have normal intelligence, and some may be retarded. Autism is not an emotional problem.
Autism is a neurological condition which people are usually born with.
Psychological trauma doesn't cause it. Autism is not a psychosis or lack of reality contact. People do not choose to be autistic. Autistic people have some disadvantages, but some live very happy and rewarding lives.