Autism is one of three disorders in Autism Spectrum disorder. It is related to brain abnormalities, but the cause is debated. Some believe the causes are heredity and birth defects, while others believe the heavy metals in vaccines and some fish (You might remember Jenny McCarthy's activisim against vaccinations for children due to her son's autism). The signs usually begin to show up in the first few years of life. A young child with early signs of autism might not make eye contact with his parents or smile like other children his age and not interact socially with other children. Autistic children don't experience personal connections and affection as others do. Imagine eating lunch with an autistic friend every day at school; every day in the hallway he walks by, waves his left hand and says robotically "hi." Then you see him in the mall years later and hurry excitedly over to him; he keeps walking, waves his left arm and says "hi."