Which of the Following Reduces the Value of Twin Studies

Multiple Choice

Which of the following reduces the value of twin studies as evidence for the role of heredity in determining IQ?

A) Twins who are reared apart are usually placed in adoptive homes that are similar in socioeconomic and ethnic backgrounds (i.e.similar environments)
B) There have been so few cases of identical twins who were separated at birth that the research results are inconclusive.
C) If heredity alone were responsible,for IQ similarity,all family members would have identical IQ scores.
D) Identical twins who were not reared together usually have very different IQ scores.