I. Genetic factors Genetic factors have a role in the development of schizophrenia. The main genetic studies on schizophrenia include: 1, family surveys found that the prevalence rate among relatives is about 10 times higher than that of the general population, and the closer the blood relationship with the patient, the higher the prevalence rate; 2, dizygotic studies reported that the rate of monozygotic twins is about 4-6 times higher than that of dizygotic twins with the same disease; 3, foster child surveys also suggest a clear genetic predisposition; 4, cytogenetic and molecular genetic studies so far lack consistent results. The mode of inheritance of schizophrenia is still uncertain, and it is believed that schizophrenia is polygenic. That is, the inheritance of schizophrenia is the result of the cumulative effect of multiple genes, with a genetic threshold, beyond which the disease appears. It is also believed that schizophrenia families, like diabetic families, are the result of a combination of genetic susceptibility and environmental factors. Whether the heritability of schizophrenia is apparent or not is determined by the impact of environmental factors on the patient. Mednick et al. (1987) suggested that the main factors influencing the later development of schizophrenia in patients with partial schizotypal personality disorder were perinatal injuries, instability in early life, and lack of parental care. In the United States, a community survey near New York found that the prevalence of schizophrenia was nine times higher in the lower social classes than in the higher classes. A related survey in 12 regions of China found that the prevalence of schizophrenia was 1,016% in the low economic class, significantly higher than 0,475% in the high economic class, which may be related to poor material life, heavy psychological burden and more psychosocial stress. Third, the age factor adolescence endocrine system development gradually mature, the vegetative nervous system instability, emotional volatility, sensitive to external stress factors. Schizophrenia is likely to occur in this period, which may be related to endocrine changes.