From disabilities.lds.org

"Autism is a disability with characteristics that vary across a wide spectrum. While persons with autism can't be identified by their physical appearance, they have similar attributes that can be observed. They usually have difficulties with language or communication, social skills and behavior, often due to sensory difficulties. Children with severe autism may be nonverbal and seem unaware of other people. Those with mild autism can appear to be incredibly smart, but may seem very odd in social interactions. Most people with autism are somewhere in the middle. Even though they have difficulty expressing their feelings and relating to others, people with autism still sense how others feel about them.

"Whether a person's autism is mild, moderate, or severe, it is commonly accepted to be a lifelong developmental disability. The exact causes of autism are unknown; however, it is a brain-based disorder. It is clear that individuals with autism are born with the disorder or born with the potential to develop it. Autism is not caused by bad parenting."