School Performance of Adult Schizophrenics, Their Siblings and Age Mates

In a previous paper, a preliminary report (Offord and Cross, 1971) found that adult schizophrenics differed in their school performance from both their siblings and their age mates. For instance, the pre-schizophrenics were significantly more likely than their siblings to have repeated at least one grade in elementary school and to have scored significantly lower on childhood IQ, tests than their siblings and age mates.