Well there's a great deal of active research trying to determine the causes of autistic disorder and other pervasive developmental disorders. What we do know is that autism definitely is linked to abnormalities within the brain. And many different studies have looked at differences between the brains of children with autistic disorder and those who do not. What we do know is that there is a very strong genetic factor. And we know this based on the success we've had with twin studies. What we do know is that fraternal twins if one twin is diagnosed with autism, it's quite common for the other twin to have some sign or symptom of this pervasive developmental disorder.
We also understand this to be true, as well, from sibling studies. What we do know is that autism tends to impact males more than females, and so there's a good deal of research looking into the genetic components of parents, as well. So keep in mind there's a great deal of information and misinformation about what causes and does not cause autism. But what we do know, at this point in time, that there is a genetic link and research continues to move forward.