"This is similar to risk for diabetes, which is very strongly affected by exercise, weight and sugar consumption, but some people can be coach potatoes and eat what they want and don't get sick. Those with a more resilient genetic predisposition for autism may get the same environmental factors without ill effect," Burmeister explained.
But the findings that suggest genetics may play a stronger role than environmental factors may be a small measure of comfort for parents like Hotez, who may have blamed themselves for their child's condition.
"In my heart now I know it's a genetic disorder," she said. "I don't think it's caused by any of the environmental [factors] they talk about in the news."