Table 2.

Twin Correlations and Univariate ACE estimates (95% Confidence Intervals).

Variable	MZ	DZ	A	C	E
Externalizing	.74	.40	.76 (.65, .79)	.00 (.00, .11)	.24 (.21, .26)
Academic Achievement & Engagement	.77	.42	.72 (.57, .79)	.05 (.00, .19)	.23 (.20, .26)
Antisocial Peers	.70	.51	.42 (.28, .58)	.28 (.13, .42)	.30 (.26, .33)
Prosocial Peers	.66	.44	.41 (.25, .59)	.24 (.08, .39)	.34 (.31, .38)
Mother-child Relationship Problems	.79	.56	.49 (.38, .62)	.30 (.17, .41)	.21 (.18, .23)
Father-child Relationship Problems	.83	.75	.23 (.15, .31)	.62 (.54, .69)	.15 (.14, .18)
Stressful Life Events	.81	.80	.08 (.01, .15)	.75 (.68, .80)	.17 (.16, .20)

Note. MZ = monozygotic; DZ = dizygotic; A = additive genetic; C = shared environment; E = nonshared environment.