Studies of monochorionic and dichorionic twins

Question

Quizplus · Accepted Answer

Studies of monochorionic and dichorionic twins have shown that monochorionic twins (who share a placenta and therefore have more shared prenatal environmental factors) have a higher risk of both developing schizophrenia if one twin is affected. This suggests that there is a role for the prenatal environment in the development of schizophrenia.

Answer: B 
 Twin studies have consistently demonstrated a high degree of heritability for schizophrenia. In dichorionic twins (who have separate placentas), the risk of developing schizophrenia is higher when the co-twin is affected, indicating a genetic component to the disorder.

Answer: C 
 Studies of monochorionic and dichorionic twins have shown that prenatal environmental factors can play a role in the development of schizophrenia. However, these studies do not suggest that the risk of developing schizophrenia is not altered by the prenatal environment.

Answer: None of the above 
 The statement "establish that genetic relatedness to an affected individual has nothing to do with one's risk of developing schizophrenia" is incorrect. Twin studies have consistently shown that genetic factors play a significant role in the development of schizophrenia, and that individuals who are genetically related to someone with the disorder are at higher risk of developing it themselves.

Studies of Monochorionic and Dichorionic Twins