. Author manuscript; available in PMC: 2017 Jul 21.

Published in final edited form as: Dev Psychopathol. 2015 Nov 27;28(2):517–526. doi: 10.1017/S0954579415001091

Table 2.

Intra-pair twin correlations and proportions of variance for the best-fitting models for Attention and Activity (95% confidence intervals)

	r_mz	r_dz	a²	c²	e²	% A transmitted from previous age	% C transmitted from previous age
Attention
Age 12	0.74 (0.64 – 0.81)^*	0.08 (−0.12 – 0.27)	0.73 (0.64–0.79)^*	0	0.27 (0.21–0.36)^*	---	---
Age 14	0.77 (0.70–0.83)^*	0.36 (0.22–0.49)^*	0.54 (0.44–0.63)^*	0.22 (0.15–0.30)^*	0.24 (0.19–0.31)^*	100%	---
Age 16	0.84 (0.77–0.89)^*	0.53 (0.37–0.66)^*	0.69 (0.54–0.80)^*	0.13 (0.04–0.26)^*	0.18 (0.13–0.25)^*	51.9%	100%

Activity
Age 12	0.87 (0.82–0.91)^*	0.51 (0.35–0.64)^*	0.73 (0.58–0.84)^*	0.13 (0.02–0.28)^*	0.15 (0.11–0.19)^*	---	---
Age 14	0.88 (0.84–0.91)^*	0.72 (0.63–0.79)^*	0.31 (0.19–0.46)^*	0.57 (0.41–0.68)^*	0.13 (0.10–0.16)^*	60.0%	100%
Age 16	0.94 (0.91–0.96)^*	0.75 (0.65–0.83)^*	0.42 (0.28–0.61)^*	0.51 (0.33–0.65)^*	0.07 (0.05–0.09)^*	100%	23.9%

Note: All proportions of variance calculated controlling for gender. r_MZ and r_DZ: intra-pair correlations in monozygotic and dizygotic twin pairs; respectively;

indicates significance at the p<0.05 level;

A: additive genetic influences; C: shared environmental influences; E: non-shared (individually-unique) environmental influences; a²: proportion of total variance explained by additive genetic influences; c²: proportion of variance explained by shared environmental influences; e²: proportion of variance attributable to non-shared environmental influences.