Step 1: Conceptual Foundation:
This question examines the heritability of intelligence, focusing on the influence of genetic relatedness and shared environmental factors on IQ correlations. The fundamental principles are:
- Increased genetic similarity correlates with higher IQ correlation. (Identical twins>Fraternal twins>Siblings)
- Shared environments enhance IQ correlation. (Reared together>Reared apart)
Step 2: Detailed Analysis:
Applying these principles allows us to order the groups by expected IQ correlation, from highest to lowest:
- (B) Identical twins reared together: Possess maximum genetic similarity (100%) and the most similar environments, resulting in the highest correlation.
- (D) Identical twins reared apart: Share maximum genetic similarity (100%) but experience different environments. Their correlation will remain high, though lower than identical twins reared together.
- (E) Fraternal twins reared together: Exhibit moderate genetic similarity (~50%) and high environmental similarity. Their correlation will be lower than that of identical twins.
- (A) Siblings reared together: Also have moderate genetic similarity (~50%) and high environmental similarity. Their correlation is generally found to be slightly less than that of fraternal twins reared together.
- (C) Siblings reared apart: Have moderate genetic similarity (~50%) but minimal environmental similarity, leading to the lowest correlation among the provided options.
Consequently, the descending order of IQ correlation is B, D, E, A, C.
Step 3: Conclusion:
The correct sequence from highest to lowest correlation is (B), (D), (E), (A), (C). This corresponds to option (4).