The term 'environmental factor' is often misunderstood and used incorrectly. Scientists consider anything that produces a biological or behavioral response that isn't strictly due to genes to be environmental. This includes what we eat and drink, what we breathe, what touches our skin, and the like.

• Exposure to the anti-epileptic drug valproic acid during pregnancy
• Older age of the mother or father
• High levels of air pollution during pregnancy. This association has been subjected to a systematic review and withstood scientific rigor. Genes control this association.
• Extreme illness or infection during pregnancy, including severe reactions to bacterial and viral infections (some of which can be prevented through vaccination)
• Obesity during pregnancy, premature birth, and complicationsduring birth, likely as the result of interactions with genes

Read the original article on STAT. Copyright 2017. Follow STAT on Twitter.

IMAGE: Chung Sung-Jun/Getty Images

For more on this story go to: http://www.businessinsider.com/environment-autism-toxins-2017-3?utm_source=feedburner&amp%3Butm_medium=referral&utm_medium=feed&utm_campaign=Feed%3A+businessinsider+%28Business+Insider%29