Which type of pairs should have the lowest correlation between their IQ scores

Question

Quizplus · Accepted Answer

Non-twin siblings who are reared apart should have the lowest correlation between their IQ scores as they share only half of their genes and their environmental factors are likely to be very different. Adoptive siblings reared together and biological parent and child who lived together could have some shared environmental factors that could increase their IQ score correlation. Identical twins reared apart, on the other hand, share all of their genes and might have some similarity in their environmental factors, leading to a higher correlation in their IQ scores.

Which Type of Pairs Should Have the Lowest Correlation Between