Below is a video discussing the genetics of autism. If one twin has autism, an identical twin has a 90% chance of having autism or an  autistic spectrum disorder. That is a very high heritability  rate. Boys are 3 to 4 times more likely to have autism than girls. No one gene is implicated; it appears to be combinations of genes that are involved.
[youtube]http://www.youtube.com/watch?v=CjdTaiJuFu0[/youtube]
