Table 2.

Brother and twin pair analyses

AnalysisGlobal intelligenceLogical intelligenceVerbal intelligenceVisuospatial intelligenceTechnical intelligence
Brother pairs
    n268,496257,591257,352257,351255,635
    b0.1720.1770.1430.1140.113
    95% CI0.168–0.1760.173–0.1810.140–0.1470.110–0.1180.108–0.117
    R20.270.230.200.160.18
DZ twin pairs
    n1,7151,6761,6761,6761,672
    b0.1360.1520.1040.0540.096
    95% CI0.089–0.1820.103–0.2020.057–0.1520.005–0.1040.047–0.144
    R20.300.250.210.150.19
MZ twin pairs
    n1,4321,3911,3941,3941,377
    b0.1280.1140.1130.0990.060
    95% CI0.084–0.1720.062–0.1660.059–0.1660.039–0.1590.003–0.118
    R20.660.530.460.370.43
Bivariate heritability
    r (DZ)0.140.140.130.080.08
    r (MZ)0.200.210.200.130.13
    Heritability0.140.150.140.100.10
    Shared environment0.070.060.060.030.03
    Non-shared environment0.790.790.800.870.87
  • The association between cardiovascular fitness and cognitive performance within brother and twin pairs. r2=adjusted coefficient of determination; b=regression coefficient presented with 95% confidence intervals. Bivariate heritability: By comparing correlation coefficients (r) between dizygotic (DZ) and monozygotic (MZ) twin pairs, bivariate heritability and contribution of shared and non-shared environment for associations between cardiovascular fitness and intelligence scores wee calculated. env=environment.