Identical twins reared in different environments correlate in intelligence about:

1. Identical twins reared together correlate almost 0.90. 2. When identical twins are reared in different environments, the correlation falls to 0.72. 3. The fall shows a role for environment, but 0.72 is still high, which shows a strong role for heredity. _Source: NCERT Class XII Psychology, Ch 1 Variations in Psychological Attributes, "Intelligence: Interplay of Nature and Nurture", p. 9_