The late English psychologist Cyril Burt was known for his studies of the IQ scores of identical twins who were raised apart. The high correlation between the IQs of separated twins in Burt's studies pointed to heredity as a major factor in IQ. (Correlation measures how closely two variables are connected.) Burt wrote several accounts of his work, adding more pairs of twins over time. Here are his reported correlations as he published them.
-----------------------------------
Publication
Date/ Twins reared apart/ Twins reared together
1955/ 0.771 (21 pairs) / 0.944 (83 pairs)
1966/ 0.771 (53 pairs) / 0.644 (95 pairs)
What is suspicious here?
1 answer
In 1966, twins reared together have lower correlation than those raised apart.
32 answers