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. Author manuscript; available in PMC: 2014 May 13.
Published in final edited form as: Psychol Sci. 2009 May 15;20(6):753–762. doi: 10.1111/j.1467-9280.2009.02366.x

TABLE 2.

Genetic, Shared Environmental, and Nonshared Environmental Correlations

Correlation IQ at 9–
SPAs at 9		 IQ at 9–
Ach at 9		 SPAs at 9–Ach
at 9		 IQ at 7–
SPAs at 9		 IQ at 7–
Ach at 10		 SPAs at 9–
Ach at 10
Genetic (rA) .53 (.29– .79) .66 (.55– .77) .65 (.47–.89) .53 (.53– .55) .59 (.48–.63) .76 (.64– .96)
Shared environmental (rC) .09 (.00– .30) .62 (.58– .83) .06 (.00–.77) .00 (.00– .30) .49 (.45–.51) .00 (.00– .85)
Nonshared environmental (rE) .38 (.34– .52) .29 (.17– .29) .30 (.21–.40) .19 (.04– .19). .29 (.29–.38) .30 (.30– .33)

Note. Numbers in parentheses are 95% confidence intervals (CIs); CIs that include 0 indicate nonsignificant correlations. The cross-sectional analyses included 1,217 pairs of monozygotic twins and 1,070 pairs of dizygotic twins; the longitudinal analyses included 1,966 pairs of monozygotic twins and 1,819 pairs of dizygotic twins.

Ach = achievement; SPA = self-perceived ability.