Table 2.

Tetrachoric twin correlations (r) with 95% confidence interval (95%CI) for 18-25 year old twins from two birth cohorts

	1993-1995		2009-2010		Combined (1993-1995 & 2009-2010)
	r	95%CI	r	95%CI	r	95%CI
MZM	.82	.70-.90	.75	.43 - .91	.80	.70 - .88
DZM	.51	.30-.67	.37	.04 - .72	.47	.29 - .63
MZF	.77	.66-.85	.80	.65 - .89	.78	.70 - .85
DZF	.69	.55 -.81	.66	.44 - .81	.67	.55 - .77
DOS	.40	.26 - .54	.34	.11 - .54	.38	.25 - .49