evidence: Vaccines do not cause autism or mercury toxicity. The amount of mercury that infants receive through their diet is more than twice the amount ever contained in vaccines. Scientific evidence shows that autism spectrum disorder (ASD) arises through a combination of genetics and environment. Twin studies demonstrate a strong heritable component to ASD, with heritability estimates ranging from about 30 to 90%. Many genes involved in ASD risk are associated with brain and neuronal development.