A study of fraternal and identical twins, at least one of each pair diagnosed with autism, shows that the main cause of this condition is genetic, not environmental as some have feared. See the story in The Daily Mail (U.K.). Hat tip to Lucianne.com for the link.
What they found, of course, is that if one identical twin was autistic, almost always both were. This was not the case for fraternal twins, where the sibling was occasionally autistic, perhaps once in four pairs.
To what should we attribute the increase in autism diagnoses? The article suggests better screening. I speculate we will eventually learn that something we believe benign is actually causing genetic damage to parents' reproductive cells. The problem: we don't know what that "something" might be.
