Not that I'm ruling out environmental factors, as it would be silly to take a definitive stance on such a murky issue, but I firmly believe autism is primarily genetic, going by current scientific developments.
That being said, it almost seems rather silly attempting to develop a cure for a condition that we do not even understand. Perhaps we should recognize what we are trying to fix before trying to repair it. I also think it seems misleading to group the entire autism spectrum into one group. A person with Asperger's has very mild autism, and in many cases simply comes off as an eccentric NT, often times being more intelligent than their neurotypical brethren in their field of interest. Then, on the other side, we have severe autism in which the person is mentally ret*d and completely unable to cope with reality. In the former situation, a touch of autism may actually be beneficial, though in the latter case, a "cure," or whatever you may call it would be a blessing.