EPPP Practice Test 2026 – Complete Exam Preparation Guide

The correlation for IQ scores among biological siblings who are reared together is typically around .85. This high correlation suggests that genetics and shared environment significantly influence IQ. When siblings share both genetic material and a common upbringing, their IQs tend to be more similar than those of unrelated individuals.

A correlation of .65 might reflect a scenario with less shared environment or differences in individual development, but it does not capture the strong genetic and environmental influence present in siblings raised together. Meanwhile, .45 and .25 correlations would indicate even weaker relationships, suggesting minimal shared influences, which is not reflective of the substantial overlap in experiences and genetics that siblings experience when reared under the same roof. Thus, the most accurate representation of the correlation in this context is .85, demonstrating a strong connection between the IQs of biological siblings who grow up together.