There seems to be a lot of discussion lately about what causes autism (see, for example, this recent column by Robert F. Kennedy Jr., Vaccines and Autism: Looking for the Truth? Study the Amish). Most of what I've read focuses on preservatives in childhood vaccinations as the cause. But an interesting op-ed in yesterday's New York Times, The Male Condition, by Simon Baron-Cohen (the director of the autism research center at Cambridge University) hypothesizes that genetics, rather than environmental factors, may be the cause of autism:
One needs to be extremely careful in advancing a cause for autism, because this field is rife with theories that have collapsed under empirical scrutiny. Nonetheless, my hypothesis is that autism is the genetic result of "assortative mating" between parents who are both strong systemizers. Assortative mating is the term we use when like is attracted to like, and there are four significant reasons to believe it is happening here.
The reasons he outlines sound pretty compelling to me, and I look forward to seeing further research that could support his assertions.