Table 1.

Intrapair twin correlations for risk-taking propensity by age and sex.

	T1(12)	T2(12)	T1(14)	T2(14)
MZ pairs
T1(12)	1.00	.30** (.09, .49)	.59*** (.43, .72)	.58*** (.33, .75)
T2(12)	.18 (−.03, .38)	1.00	.51*** (.24, .71)	.63*** (.40, .79)
T1(14)	.26** (.08, .42)	−.04 (−.30, .22)	1.00	.60*** (.36, .77)
T2(14)	.10(−.16, .35)	.12 (−.15, .37)	−.11 (−.36, 16)	1.00
DZ same-sex pairs
T1(12)	1.00	−.01 (−.24, .22)	.41*** (.21, .58)	.02 (−.29, .33)
T2(12)	.06 (−.22, .34)	1.00	−.03 (.33, .28)	.45** (.17, .67)
T1(14)	.43** (.17, .64)	−.36 (−.67, .05)	1.00	.19 (−.12, .47)
T2(14)	.21 (−.21, .57)	.49** (.11, .75)	.22 (−.20, 57)	1.00
DZ opposite-sex pairs
T1(12)	-	-	-	-
T2(12)	.24* (.03, .43)	-	-	-
T1(14)	.33*** (.16, .48)	.15 (−.11, .39)	-	-
T2(14)	.00 (−.25, .25)	.29* (.04, .50)	.08 (−.18, .33)	-

For the same-sex MZ and DZ pairs, male and female twin correlations are shown above and below the main diagonal, respectively. T1 and T2 are co-twins of the same pair; age of assessment is shown in brackets. Intrapair twin correlations at ages 12 and 14 are shown in bold face; other coefficients represent cross-age, cross-twin correlations and within-twin, cross-age correlations. Significance levels (two-tailed):

^*p<0.05;

^**p<0.01;

^***p<0.001; lower and upper bounds of the 95% confidence intervals are shown in brackets.