Controversial twin study challenges idea that genes determine autism risk
A study of twins in California downgrades the role genes play in autism, but the work doesn’t hold water with some autism researchers.
Previous studies indicated that autism spectrum disorders are due mainly to genes. But the new study suggests that environment — including conditions in the womb, age of parents and other factors — may account for a greater fraction of the risk of developing autism spectrum disorders.
“People are, more and more, recognizing that autism is a complex disorder that would be hard to explain with genes alone,” says study coauthor Joachim Hallmayer, a psychiatric geneticist at Stanford University.
But some researchers question whether the new estimates accurately reflect the contributions of genes and environment to autism. “When somebody gets a totally different answer from what anyone else has seen, you need to see it a few more times before you believe it,” says Susan Folstein, a chi