Researchers Who Have Analyzed IQ Scores of Adopted Twins Have

Researchers who have analyzed IQ scores of adopted twins have found that identical twins are more like one another in IQ than fraternal twins are. They also have found that IQs of adopted children are more strongly correlated with the IQs of their biological parents than with the IQs of their adoptive parents. These research results suggest

A) that environment has no impact upon IQ.
B) that intelligence has a genetic component.
C) that a child's intellectual capacity is fixed at birth.
D) that a child's biological heritage predicts her lifetime patterns of achievement and accomplishment.