Environment may play a bigger role in autism than genetics. Photo courtesy of SeRVe Photography

Autism has long been considered among the most heritable of developmental brain disorders. But a new study of autistic twins indicates that shared environment has a larger impact on the development of autism and autism spectrum disorders than previously thought, and is in fact more important than genetics.

Researchers from Stanford and UC San Francisco examined the prevalence of autism among both identical and non-identical twin pairs. The frequency of identical twins both being diagnosed with autism was lower than would be predicted from statistical models of heritability. The scientists estimate that environmental factors common to twins explains 55% of susceptibility to autism, whereas genetics accounts for only 37%.

Another study published in the same issue of Archives of General Psychiatry suggests that the use of antidepressants by mothers doubles the risk of a child developing autism. Other environmental factors that could be important in autism risk include diet, pollution, parental age, birthweight and maternal infections during pregnancy.

New Study Suggests Autism More Tightly Linked To Environment Than Genetics 24 April,2013Darya Pino

  • Larissa

    Interesting new findings…as the believed cause for Autism has changed so many times in the last several years, I wonder how close we are to truly knowing…

  • Kim Stiving

    Larissa, that was my first thought as well…I’m not sure this study has provided us with anymore clarity about Autism than we’ve had before. The environmental factors that have been listed (use of antidepressants, diet, age, etc.) are all factors that could lead to a vast array of other disorders/diseases in children. If anything, the findings have just added to the mystery that is Autism.


Darya Pino

Darya Pino is a Ph.D trained scientist, San Francisco foodie, food and health writer and advocate of local, seasonal foods. She shares her unique scientific perspective on health and enthusiasm for delicious foods at her website Summer Tomato. Follow her on Twitter @summertomato.

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