IQ Correlation Ranking: Nature vs. Nurture

Nature vs. Nurture studies examine how genetics (nature) and environment (nurture) influence traits like IQ. IQ correlation is typically highest when individuals share both high genetic similarity and a similar environment.

Key Principles for IQ Correlation

• Genetic Similarity: Identical twins share 100% of their genes, while fraternal twins and siblings share about 50%.
• Environmental Influence: Shared environments tend to increase IQ correlation, whereas different environments decrease it.

Arranging IQ Correlations (Highest to Lowest)

Based on these principles, the expected order of IQ correlation is:

1. (C) Identical twins reared together: Highest correlation due to 100% shared genes and a shared environment.
2. (A) Identical twins reared in different environments: Still high correlation due to 100% shared genes, but lower than those reared together.
3. (B) Fraternal twins reared together: Moderate correlation from ~50% shared genes and a shared environment.
4. (E) Siblings reared together: Similar to fraternal twins (~50% shared genes, shared environment), often slightly less correlated than fraternal twins reared together.
5. (D) Siblings reared apart: Lowest correlation among these groups due to ~50% shared genes but differing environments.

Therefore, the order from highest to lowest IQ correlation is (C), (A), (B), (E), (D).