Listen, as Dr. Volkmar explains the causes of autism.
At the moment, the best evidence will suggest a very strong genetic basis for autism. If you look at the rate of autism in identical as opposed to fraternal twins, identical twins sharing the same genetic environment, although, interestingly, not all of the same intrauterine environment, the rate for autism is about 60% for identical twins. You start to broaden your definition, you get up to about 90%, whereas fraternal twins it is much lower, which very strongly suggests genetic factors.
It looks like there are multiple genes involved in autism, and that seems to be the hardest part of the genetics. But at the moment we are looking very actively at several potential genes that may be involved.
About Dr. Volkmar, M.D.:
Fred Volkmar, M.D. is the director of the Yale University Child Study Center and Irving B. Harris Professor of Child Psychiatry, Pediatrics and Psychology at Yale University, where he heads the university's autism research and autism clinic. He is also Chief of Child Psychiatry at Yale-New Haven Hospital. His research focuses on understanding the fundamental nature of autism and developing better guidelines to diagnose autism and related conditions.