Cole and Daniel are brothers, born 18 months apart. Eric and Frank are brothers, born 6 years apart. Which of the following is TRUE regarding the correlation between the IQ scores of Cole and Daniel on the one hand and that between the IQ scores of Eric and Frank on the other?
A) Cole's and Daniel's scores are more highly correlated than those of Eric and Frank.
B) The correlation is near zero for each pair of brothers.
C) Eric's and Frank's scores are more highly correlated than those of Cole and Daniel.
D) The correlation coefficient between Cole's and Daniel's scores is probably very similar to that between the scores of Eric and Frank.

Question

Quizplus · Accepted Answer

Research in behavioral genetics suggests that siblings closer in age, like Cole and Daniel, tend to have more similar environments and experiences, which can lead to a higher correlation in IQ scores compared to siblings further apart in age, like Eric and Frank.

Cole and Daniel Are Brothers, Born 18 Months Apart