Environment and inheritance: opposing forces?

High risk of schizophrenia requires high genetic predisposition to develop schizophrenia, plus an environmental trigger. A schizophrenic family environment is commonly believed to represent this trigger. The hypothesis is presented here that, on the contrary, a high predisposition to schizophrenia in significant others protects against overt illness. The trigger may be the predominance around the index individual of significant others with low predisposition to develop schizophrenia.