Autism diagnoses in the U.S. have risen sharply in the past two decades, with the CDC estimating that 2.77% of 8-year-olds were diagnosed by 2020. Researchers attribute part of this increase to broader definitions and better awareness, while ongoing studies explore environmental and genetic factors. RFK Jr., who has previously promoted debunked vaccine theories, has pledged to identify the causes of autism by September—an ambitious goal many experts say oversimplifies a highly complex condition.