Little is known about what causes the condition although genetic and environmental factors like the MMR jab and poor diet have been implicated. A paper published by Professor Simon Baron-Cohen from Cambridge University in the June 2002 issue of Trends in Cognitive Sciences suggests that something called "male brain syndrome" could play a significant part.
Professor Baron Cohen suggests that men who are drawn to work in areas like computing may be carrying a larger than normal number of the genes which cause autism. If they have children with a partner carrying a coincidentally high proportion of these genes it may increase the likelihood of them having a child with autism.