Even when identical twins are reared apart, they still tend to be very similar in personality. How is this strong evidence that genes contribute to personality?
A) Identical twins who were reared apart were most likely treated in very similar ways.
B) The similarities remain, even though there were probably significant differences in how the siblings were raised.
C) There are fewer similarities when twins are reared together.
D) Actually, identical twins who are raised apart show very little similarity.

Question

Quizplus · Accepted Answer

The fact that identical twins who were reared apart still tend to be very similar in personality suggests that there is a strong genetic component to personality, as environmental factors (such as upbringing) are likely to be different between the twins. Therefore, the similarities remaining despite differences in upbringing strongly suggest a genetic influence on personality. Option A is incorrect because the similarities between twins could also suggest that both twins were treated very differently by their adoptive families, which would contradict the hypothesis that genetics play a role in personality. Option C is incorrect because there are generally more similarities between twins who were reared together than those who were reared apart. Option D is incorrect because research has shown that identical twins who are raised apart actually do show significant similarity in personality.

Even When Identical Twins Are Reared Apart, They Still Tend