The following are possible causes of mild autism: 1. It may be caused by genetic factors, because autism is a psychiatric disorder caused by genetic factors, and if both parents and grandparents have psychiatric disorders, such as anxiety, depression, or schizophrenia, the probability of the child developing autism is greatly increased. 2. If the child is under stress or encounters many stressful events, he or she is more likely to have mild autistic symptoms and performance. 3. It is also possible that maternal illness, puerperal infection, anxiety, stress, depression, etc. may occur during pregnancy.