Genetic Basis AO3

• +Strong evidence base. Family studies show risk increases with genetic similarity. Twin studies found 33% concordance for MZ twins and 7% for DZ twins (Hilker). Adoption studies show that biological children of parents of schizophrenia are at greater risk even if they grow up in an adoptive family. This shows that some people are more vulnerable to schizophrenia because of their genes.
• -Environmental risk factors. Biological risk factors include birth complications (Morgan) and smoking THC - rich cannabis in teen years (Di Forti). Psychological risk factors include childhood trauma; 67% with schizophrenia (38% matched controls) reported at least one childhood trauma (Mørkved). This means genes alone cannot provide a complete explanation for schizophrenia.
• Genetic Counselling

  If potential parents have a relative with schizophrenia, they can be advised of the risk of having a child with the condition. The risk estimate is an average figure based on genetic similarity to relatives and doesn’t take into account the child’s future environment. This means that genetic counselling only provides a crude idea of vulnerability and is of limited use.