Which of the following is the best evidence for a genetic contribution to intelligence?
A) the high correlation between intelligence scores of close biological relatives
B) the fact that aptitude test scores of identical twins reared together tend to be more highly correlated than the scores of identical twins reared apart
C) the fact that intelligence scores of identical twins tend to be more similar than those of fraternal twins
D) the fact that intelligence scores of fraternal twins tend to be more similar than those of non-twin siblings

Question

Quizplus · Accepted Answer

Identical twins share 100% of their genes, so the higher similarity in their intelligence scores compared to fraternal twins, who share about 50% of their genes, suggests a genetic contribution to intelligence.

Which of the Following Is the Best Evidence for a Genetic