The evidence from studies of twins and biological and adoptive siblings indicates that shared environmental influences explain approximately _____ percent of individual variations in personality traits.
A) 0 to 10
B) 15
C) 25
D) 50

Question

Quizplus · Accepted Answer

The studies of twins and biological and adoptive siblings suggest that shared environmental influences account only for a small fraction (0-10%) of individual variations in personality traits. This conclusion is based on the fact that identical twins, who share nearly all their genetic makeup and usually are raised in the same environment, are typically more similar in personality than fraternal twins, who share only about half their genes and are raised in the same environment. Likewise, biological siblings, who also share about half their genes but usually grow up together, tend to be more similar in personality than adoptive siblings who, although sharing the same environment, are not biologically related. These findings suggest that genetic factors and non-shared environmental factors (i.e., experiences that are unique to each individual) play a more significant role in shaping personality traits than shared environmental factors.

The Evidence from Studies of Twins and Biological and Adoptive