What important aspect of the adoptive family was missing from early studies? Wh

Early studies did not examine child rearing adequacy of the adoptive family.  Newer studies found that communication deviance - how understandable and easy to follow the speech of family members was - was related to risk of schizophrenia.  Children with a biological risk for schizophrenia who were adopted into families with high communication deviance had an increased risk of the disease.  If the child had no genetic predisposition for schizophrenia, communication deviance did not make a difference in risk.  Most interestingly, if a genetic risk existed and the child was adopted into a family with low communication deviance, that child's risk for schizophrenia was actually lower than the other groups!