The largest and most rigorous autism twin study thus far conducted has confirmed what many, researchers, doctors and parents alike, had suspected for some time - that shared environmental influences play a large part in the development of the spectrum of developmental disorders.
In fact the study tips the balance for the first time towards environmental factors being a more important determining factor for a child developing an autism spectrum disorder (ASD) than their inherited genetic make-up.
The study involved a total of 192 pairs of twins drawn from the general population with the study being supported by the National Institutes of Health (NIH) and involving researchers from the Autism Genetic Resource Exchange, California Department of Public Health, Kaiser Permanente, and the University of California, Davis. The research was partially funded by advocacy group Autism Speaks. The findings of the study, known as the California Autism Twins Study (CATS), were reported in the July 2011 issue of the journal Archives of General Psychiatry.