Contrary to decades of prior research, a new study of 192 sets of twins concluded that environmental factors, not genetics, accounts for the majority of the risk associated with autism spectrum disorders. Autism experts roundly criticized the findings, according to the Los Angeles Times.

The data in the study, published online July 4 in the Archives of General Psychiatry, was in line with previous studies: autism concordance rates of 77 percent for identical twins and 31 percent for fraternal twins. Yet when plugged into a statistical computer model to determine contributing roles of genes and the environment, the team concluded that only 38 percent of the risk for autism came from genetics while roughly 58 percent came from the environment shared by the twins.

"Their data are so similar to everybody else's, and yet they come up with another conclusion," Robert Plomin, a behavioral...

The study authors admitted their calculations were subject to a wide margin of error, and could be incorrect, the Times reported. Still, they argued that the findings highlight the need for more research into contributing environmental factors in autism.

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