Researchers from all over the world are now devoting considerable time and energy into finding the answer to this critical question. Medical researchers are exploring different explanations for the various forms of autism. Although a single specific cause of autism is not known, current research links autism to biological or neurological differences in the brain. In many families there appears to be a pattern of autism or related disabilities -- which suggests there is a genetic basis to the disorder -- although at this time no gene has been directly linked to autism. The genetic basis is believed by researchers to be highly complex, probably involving several genes in combination.

Several outdated theories about the cause of autism have been proven false. Autism is not a mental illness. Children with autism are not unruly kids who choose to not behave. Autism is not caused by bad parenting. Furthermore, no known psychological factors in the development of the child have been shown to cause autism.