>>190896752Schizophrenia is a complex disease, meaning that the pathogenesis is always a combination of genetic predisposition and environmental factors. Compared to other complex diseases, schizophrenia has a rather moderate genetic component as shown by twin studies and later genome-wide association studies. Moreover, there are few Mendelian syndromes that mimic schizophrenia, meaning that there is no single definitive causal "schizophrenia gene". Environmental factors that contribute to this disease include
Heavy, traumatic birth
Low birth weight
Very early childhood trauma (parental separation, sexual trauma etc.)
Early social isolation
and many more which are disputed
source: molecular geneticist with 3 published articles on complex diseases in journals with an impact factor
