Autism is mainly caused by genetic factors, but also has some environmental factors as influencing factors. However, autism, as a more serious mental illness in childhood, is most often caused by genetic factors, such as the possibility of accompanying polygenic genetic problems or genetic mutation problems. From a statistical point of view, if an immediate family member within three generations has autism or anxiety disorder, or if a collateral family member within three generations has autism, the probability of autism in the affected child increases greatly, and may be several to ten times higher than in the general population.