Average Risk of Developing Schizophrenia The risk of schizophrenia among biological relatives is greater for those with greater degrees of relatedness. An identical (MZ) twin of a twin with schizophrenia has a 48% risk of developing schizophrenia, for example, and offspring of two parents with schizophrenia have a 46% risk of developing the disorder.

Adapted from Gottesman, 1991.