TABLE II.

Tetrachoric correlations and 95% CIs for asthma and obesity according to zygosity^*

	Twin 1		Twin 2
	Asthma	Obesity	Asthma	Obesity
Monozygotic (n = 1001)
Twin 1
Asthma	1.000
Obesity	0.13 (0.00–0.27)†	1.000
Twin 2
Asthma	0.51 (0.40–0.62)‡	0.13 (0.00–0.28)§	1.000
Obesity	0.10 (0.00–0.25)§	0.77 (0.68–0.83)‡	0.20 (0.05–0.35)†	1.000
Dizygotic (n = 383)
Twin 1
Asthma	1.000
Obesity	0.17 (0.00–0.38)†	1.000
Twin 2
Asthma	0.34 (0.14–0.52)‡	0.00 (0.00–0.19)§	1.000
Obesity	0.13 (0.00–0.33)§	0.38 (0.18–0.55)‡	0.41 (0.21–0.58)†	1.000

^*The correlations and 95% CIs have a lower bound of zero.

^†Phenotypic correlation between asthma and obesity.

^‡Twin correlations.

^§Cross-twin, cross-trait correlation.