A new study showed that environmental factors may play a larger role in the development of autism than previously recognized, according to media reports on Tuesday. The new study in the Archives of General Psychiatry looked at 192 pairs of twins in California. It found autism was surprisingly common in fraternal twins, despite the fact that they don’t share as many of the same genes as identical twins, suggesting that something in their mutual life circumstances may be playing at least as strong a role as genetics. The study, which will likely be followed up with similar studies of twins and other siblings, could  force a dramatic swing in the focus of research into the developmental disorder. “It looks like some shared environmental factors play a role in autism, and the study really points toward factors that are early in life that affect the development of the child,” said study researcher Joachim Hallmayer, MD, an associate professor of psychiatry at Stanford University in California.