Dr Hardhead Has Developed a Measure of Stubbornness and Wants

Multiple Choice

Dr. Hardhead has developed a measure of stubbornness and wants to determine the influence of genetics on performance on his new measure. Which of the following findings from administrations of the new test provides the best evidence for genetic influence?

A) Scores are more highly correlated in identical twins reared together than identical twins reared apart.
B) Scores are more highly correlated in identical than fraternal twins.
C) Scores are highly correlated between adopted children and their adoptive parents.
D) Scores are highly correlated between siblings.