The existence of MZ twin pairs in which only one has autism suggests that
A) some MZ twins are really dizygotic.
B) the environment contributes to autism.
C) twins cannot become autistic.
D) the parents are medicating only one twin, as part of a clinical trial.
E) genes do not contribute to causing autism.

Question

Quizplus · Accepted Answer

The fact that only one twin in an MZ pair has autism suggests that the environment must play a role in the development of autism. Since MZ twins share identical genes, any differences in autism status must be due to differences in their environment or random chance. This supports the idea that both genetic and environmental factors contribute to the development of autism.

The Existence of MZ Twin Pairs in Which Only One