Also, autism works on a scale so when people say it is ONLY genetic they aren't correct. Environmental causes can and will make cases worse and more common. Genes are one part but the health of the mother, introduction to vital microbes at an early age and environmental causes like pollution and poor diet increase the severity anf chances of autism. Emeran Mayer is my source and he is the executive Director of the Oppenheimer Family Center for Neurobiology of Stress, and Co-director of the CURE: Digestive Diseases Research Center at UCLA.