I had a friend who had two autistic children, that told me that the condition is hereditary and that is is very often found in children of engineers (now days, computer nerds). This could mean children of mildly Asperger people. Actually, both parents in two different families that I knew with autistic kids, could have qualified as possible Aspergers.
Heh. As a computer nerd, I'll keep that in mind.
In all seriousness, I believe that the epidemic rate in autism-like syndromes has risen is too quickly to be accounted for by genetics.
That said, I wouldn't be surprised if there is a genetic predisposition (a genetically-passed susceptibility, if you will) to whatever causes autism.
I believe there is a genetic component in SOME cases; a Stanford study indicates there are three genes with an weakness. The condition itself is not genetic, however, from their findings. I mention elsewhere a connection with lazy eye in families with autistics; my husband believes there is an issue of genetic "brain mapping" that is genetic but it is not autistic, per se. That, I think, might explain the "engineering" aspect. My husband, one son (non-autistic and very "engineering" personality) and my mother-in-law all have the lazy eye condition (only one is visible on gross examination outside the eyes, however); a relative of my mother-in-law's was a fluid dynamics engineer at NASA. I happen to think those things are all connected.
Oh, incidentally, my husband is an engineer-type, also, and his mother has an autistic-like personality.