Table 2.

Polychoric twin-correlations of the CTRS rated by same teachers (ST) versus different teachers (DT)

	Oppositional		Cognitive problems-inattention		Hyperactivity		ADHD index
	ST	DT	ST	DT	ST	DT	ST	DT
Monozygotic males	0.86	0.53	0.90	0.76	0.81	0.59	0.85	0.59
Dizygotic males	0.50	0.49	0.64	0.29	0.42	0.14	0.49	0.19
Monozygotic females	0.87	0.43	0.92	0.64	0.83	0.47	0.87	0.52
Dizygotic females	0.66	0.10	0.60	0.42	0.34	0.25	0.45	0.24
Opposite-sex twins	0.37	0.13	0.44	0.23	0.30	0.17	0.37	0.27