In which case is the correlation between IQ scores the lowest

Question

Quizplus · Accepted Answer

The correlation between IQ scores is lowest for non-twin siblings reared apart. This is because when siblings are reared apart, they are exposed to different environments, experiences, and opportunities that may have a greater impact on their cognitive development than their genetic similarity. On the other hand, twin studies (both fraternal and identical) have shown higher correlations between IQ scores, as they share a more similar genetic makeup and a more similar environment (when reared together). The correlation between IQ scores for adoptive siblings reared together is also higher than for non-twin siblings reared apart, as they share a more similar environment (although not a genetic one).

In Which Case Is the Correlation Between IQ Scores the Lowest