Similar to our previous publication22, there were increased risks of schizophrenia to first degree relatives; 9.9 (8.5–11.6) for parent-offspring and 9.0 (8.1–9.9) for full siblings. Half-sibs had a significantly increased risk, albeit substantially lower than the full-siblings. Adopted children whose biological parents have schizophrenia and biological siblings growing up in different families also had an increase in risk of being diagnosed with the same disease. There were no cases where both an adoptive parent and an adoptee had a diagnosis of schizophrenia.
