Schizophrenia follows a simple Mendelian inheritance pattern with a single dominant gene; a genetic test can definitively determine whether this patient will develop schizophrenia

Psychiatric disorders like schizophrenia have a polygenic architecture, risk is conferred by hundreds of common genetic variants each contributing small effects, combined with rare variants of larger effect and gene-environment interactions; heritability estimates of approximately 80% from twin studies indicate strong genetic contribution, but no single gene is sufficient or necessary, and current genetic testing cannot predict individual outcomes

Psychiatric disorders have zero genetic component; schizophrenia is caused entirely by environmental factors, and family clustering is explained solely by shared household environment

The 80% heritability of schizophrenia means that 80% of people with the risk genes will develop the disorder, and this patient has an 80% chance of developing schizophrenia