Researchers from all over the world are 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 a autism or related disabilities – which suggest 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.