Which one of the following findings is the best evidence that genetics plays an important role in determining intelligence?
A) Identical twins raised apart have more similar IQs than fraternal twins raised together.
B) Fraternal twins raised together have more similar IQs than nontwin siblings raised together.
C) Children have IQs that are more similar to the IQs of their siblings than to the IQs of their parents.
D) Children adopted from different biological parents but raised by the same adoptive parents have fairly similar IQs as young children.

Question

Quizplus · Accepted Answer

Identical twins share 100% of their genes, while fraternal twins share only about 50% of their genes, just like nontwin siblings. Therefore, if identical twins raised in different environments have more similar IQs than fraternal twins, it suggests that genetics plays a significant role in determining intelligence. This finding has been observed repeatedly in twin studies, providing strong evidence for the importance of genetics in intelligence.

Which One of the Following Findings Is the Best Evidence