Behavioural-genetic studies have shown that as adopted children grow into adulthood, the correlation between their IQ scores and those of their biologically unrelated family members is about 0.45.

Question

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The correlation between IQ scores of adopted children and their biologically unrelated family members tends to decrease as they grow older, often approaching zero, indicating that genetics play a larger role in adult IQ.

Behavioural-Genetic Studies Have Shown That as Adopted Children Grow into Adulthood