As someone who has worked with children who have autism for many years, I have often wondered about the importance of environmental factors. It seemed to be just too easy to say it must be due to the genes contributed by the parents than to look at the whole picture. This study, done with 192 pairs of twins in California, seems to have a diverse enough study population to give us some real insight as to what combination of factors might contribute to this disorder.
And then there are the other variables: are we diagnosing more cases because we know more about the symptoms and how to help these children develop? Were there children who now would get the diagnosis but years ago were just considered odd?
This reminds me of a conversation I had with a friend several months ago. She was commenting on the rise in the number of diagnosed cases of autism spectrum disorder as compared to when we were growing up. "When I was little, my dad used to go out into the back yard and spray DDT to kill the weeds, while smoking a cigarette and complaining about the air pollution, and I turned out fine" she said. And, while that was certainly true, did the exposure to toxins such as DDT affected the genes in her family, turning some on and/or off, which would have carried over into subsequent generations? The environment that our grandmothers and grandfathers lived in does effects us in this way. And I reminded her that she had just said that several of her friends have children who have an autism spectrum disorder diagnosis. What did not show up as often in our generation may have carried over into our children and/or grandchildren.
At this point, we don't have definitive answers. After years of hearing it was the parents'/families' fault (does anyone remember the "Refrigerator Mother" label?) it is heartening to see the research that is looking at the whole picture.