. Author manuscript; available in PMC: 2009 Nov 10.

Published in final edited form as: J Abnorm Psychol. 2009 Feb;118(1):117–130. doi: 10.1037/a0014657

Table 2.

Twin Correlations and ACE Model Parameters at Waves 1 and 2

	Wave 1 (age ~12 years)					Wave 2 (age ~17 years)
	Twin correlations		Model parameter estimates (95% confidence intervals)			Twin correlations		Model parameter estimates (95% confidence intervals)
Behavioral measure	MZ	DZ	a²	c²	e²	MZ	DZ	a²	c²	e²
Substance use	.61	.31	.58 (.24–.68)	.02 (.00–.31)	.40 (.32–.50)	.75	.65	.20 (.01–.42)	.55 (.35–.71)	.25 (.20–.31)
CD composite	.81	.46	.70 (.46–.85)	.11 (.00–.34)	.19 (.15–.24)	.75	.50	.49 (.25–.76)	.26 (.00–.46)	.25 (.20–.32)
ADHD composite	.79	.59	.41 (.17–.75)	.38 (.05–.59)	.21 (.16–.27)	.83	.57	.51 (.29–.83)	.32 (.00–.52)	.17 (.14–.27)
Novelty seeking	.50	.25	.50 (.20–.60)	.00 (.00–.24)	.50 (.40–.63)	.28	.14	.28 (.06–.41)	.00 (.00–.15)	.72 (.59–.87)

Note. Maximum-likelihood correlations estimated from the model using Mx, which uses all available data. ADHD = attention-deficit/hyperactivity disorder; CD = conduct disorder; DZ = dizygotic; MZ = monozygotic.