Question

Arrange the following from the highest to lowest level of correlation in terms of IQ:
(A) The correlation between siblings reared together
(B) The correlation between identical twins reared together
(C) The correlation between siblings reared apart
(D) The correlation between identical twins reared in different environments
(E) The correlation of fraternal twins reared together
Choose the correct answer from the options given below:

• A. (E), (D), (C), (A), (B)
• B. (C), (A), (E), (D), (B)
• C. (B), (E), (D), (A), (C)
• D. (B), (D), (E), (A), (C)

Hint:

To solve these problems, always start by ranking based on genetics (Identical Twins>Fraternal Twins/Siblings), and then use the environment (Together>Apart) as a secondary ranking factor within each genetic category.

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
This question assesses understanding of the heritability of intelligence, specifically how genetic relatedness and shared environment affect IQ correlation. The general principles are: \begin{enumerate}
Higher genetic similarity leads to higher IQ correlation. (Identical twins > Fraternal twins > Siblings)
Shared environment increases IQ correlation. (Reared together > Reared apart) \end{enumerate} Step 2: Detailed Explanation:
Applying these principles, we can rank the groups from highest to lowest expected correlation: \begin{enumerate}
(B) Identical twins reared together: Highest genetic similarity (100%) and highest environmental similarity. This will have the highest correlation.
(D) Identical twins reared in different environments: Highest genetic similarity (100%) but different environments. The correlation will be high, but lower than identical twins reared together.
(E) Fraternal twins reared together: Moderate genetic similarity (~50%) and high environmental similarity. This correlation will be lower than identical twins.
(A) Siblings reared together: Moderate genetic similarity (~50%) and high environmental similarity. The correlation is typically found to be slightly lower than for fraternal twins reared together.
(C) Siblings reared apart: Moderate genetic similarity (~50%) but low environmental similarity. This will have the lowest correlation among the given options. \end{enumerate} Therefore, the correct descending order of IQ correlation is B, D, E, A, C.
Step 3: Final Answer:
The correct sequence from highest to lowest correlation is (B), (D), (E), (A), (C). This matches option (4).