STUDIES of the parents of schizophrenics have demonstrated aberrant modes of conceptualizing and thinking in these subjects similar in nature to those shown by schizophrenics themselves.1-3 Recently Ciarlo et al4 using a Word Association Test, found the parents of schizophrenics to give more culturally deviant associations than the parents of normal subjects. These studies suggest that thinking disorders are somehow transmitted from parent to child but do not establish the roles of genetic, environmental, or other factors in this transmission.
One of the factors which seriously weakens the criticalness of studies in this respect is the fact that the parents tested not only raised their offspring but provided their genetic makeup as well. In the present study an attempt is made to disentangle biological and familial influences on the coincidence of pathological thinking in parent and schizophrenic offspring by comparing
Zahn TP. Word Association in Adoptive and Biological Parents of Schizophrenics. Arch Gen Psychiatry. 1968;19(4):501-503. doi:10.1001/archpsyc.1968.01740100117017