Table 4.
Estimates of Variance Components and Proportions of Variance in Study Educational Variables, and Their Genetic and Environmental Correlations with IQ
| -2 sd | 0 sd | 2 sd | -2 sd | 0 sd | 2 sd | |
|---|---|---|---|---|---|---|
| Primary Educational Phenotype | ||||||
| Grade Point Average at Age 17 | Educational Attainment at Age 24 | |||||
| Variance components | ||||||
| Genetic | .57 (.34,.83) |
.57 (.34,.83) |
.57 (.34,.83) |
.16 (.09,.26) |
.35 (.13,.61) |
.64 (.09,1.57) |
| Shared environmental | .21 (.00,.44) |
.21 (.00,.44) |
.21 (.00,.44) |
.96 (.79,1.13) |
.39 (.14,.61) |
.07 (.00,.68) |
| Nonshared environmental | .53 (.46,.60) |
.26 (.22,.30) |
.08 (.03,.26) |
.26 (.22,.31) |
.26 (.22,.31) |
.26 (.22,.31) |
| Proportions of variance | ||||||
| Genetic | .44 (.21,.70) |
.55 (.32,.81) |
.66 (.43,.92) |
.12 (.05,.22) |
.35 (.13,.61) |
.66 (.11,.95) |
| Shared environmental | .16 (-.05,.39) |
.20 (-.01,.43) |
.24 (.03,.47) |
.70 (.53,.87) |
.39 (.14,.61) |
.07 (.00,.68) |
| Nonshared environmental | .40 (.33,.47) |
.25 (.21,.29) |
.09 (.04,.27) |
.19 (.15,.24) |
.26 (.22,.31) |
.27 (.23,.32) |
| Correlations with IQ | ||||||
| Genetic | .62 (.35,.88) |
.62 (.35,.88) |
.62 (.35,.88) |
.57 (.31,.86) |
.38 (.12,.67) |
.28 (.02,.57) |
| Shared environmental | .12 (-1.00,1.00) |
.12 (-1.00,1.00) |
.12 (-1.00,1.00) |
1.00 (.00,1.00) |
1.00 (.00,1.00) |
1.00 (.00,1.00) |
| Nonshared environmental | .06 (-.04,.16) |
.09 (-.01,.19) |
.16 (.06,.26) |
.00 (-.13,.13) |
.00 (-.13,.13) |
.00 (-.13,.13) |
Note: The variance components are raw; they do not sum to 1.00. The proportions of variance sum to 1.00. 95% confidence intervals are given in parentheses. To the extent they hit bounds they are of course not precisely 95% confidence intervals.