Question

Consider the following results of a study of schizophrenia that is conducted using the adoptee’s family method:  

For non-schizophrenic adoptees, the occurrence of schizophrenia in both the biological and adopted families is 0%

For schizophrenic adoptees, the occurrence of schizophrenia in the adopted family is 0%

For schizophrenic adoptees, the occurrence of schizophrenia in the biological family is 5%

Based on these results, does genetics or environment play a greater role in schizophrenia? Explain your answer.

Answer 1

Based on these results, it seems that genetics plays a greater role in schizophrenia. Note that the non-schizophrenia individuals show the same rates while being raised in the same family or when adopted. On the other hand, individuals with schizophrenia show a 5 percent occurrence when raised together but 0 percent when raised apart. When they are raised together, we can eliminate large scale environmental differences that might have affected the disorder.