For years, public health debate has often fixated on a supposed rise in the prevalence of autism. Various culprits have been named, including the well-investigated but unsubstantiated claim that vaccines cause autism. More recently, additional risk factors have been proposed — many by Health Secretary Robert F. Kennedy Jr. — including maternal Tylenol use, food dyes and additives, chemical manufacturing agents and other possible stressors affecting perinatal development. Concerns about autism have been spotlighted within the larger Make America Healthy Again movement, motivated by a well-founded alarm over the nation’s devastatingly high burden of chronic disease and psychiatric illness. But there is a bigger problem with the autism epidemic: It doesn’t exist.