Those changes dramatically expanded who could receive an autism diagnosis, and some researchers and autism advocates say that has artificially inflated the sense of a burgeoning autism epidemic. Those studies consistently find autism prevalence close to 1% across generations — suggesting many people who would be diagnosed today simply went unrecognized decades ago. Once a highly stigmatized diagnosis, autism has become far more widely recognized and understood. Scientists agree that environmental factors likely contribute to autism risk in at least some children. Scientists have made enormous progress over the past two decades, identifying hundreds of autism-related genes and several established prenatal risk factors.