. 2023 Apr 21;14:17. doi: 10.1186/s13229-023-00548-3

Table 3.

Univariate models for physical health conditions

Physical health conditions	Cross-twin correlation			The proportions explained by each etiology component						Heritability reported by other studies
	Cross-twin correlation			Genetic effects		Shared environmental effects		Nonshared environmental effects		Heritability reported by other studies
		r	95% CI	A/V	95% CI	C/V	95% CI	E/V	95% CI	h²
Neurological disorders
Epilepsy	MZ	0.62	0.47, 0.75	0.61	0.24, 0.73	0		0.39	0.27, 0.54	range from 0.69 to 0.88 [20–22]
Epilepsy	DZ	0.25	0.04, 0.44	0.61	0.24, 0.73	0		0.39	0.27, 0.54	range from 0.69 to 0.88 [20–22]
Migraine	MZ	0.45	0.26, 0.60	0.41	0.07, 0.56	0		0.59	0.44, 0.75	0.45 (95% CI = 0.41, 0.49) [23] (meta-analysis)
Migraine	DZ	0.13	–0.06, 0.31	0.41	0.07, 0.56	0		0.59	0.44, 0.75	0.45 (95% CI = 0.41, 0.49) [23] (meta-analysis)
Other headache	MZ	0.54	0.35, 0.70	0.53	0, 0.69	0		0.47	0.31, 0.66	range from 0.40 to 0.45 [23] (tension-type headache)
Other headache	DZ	0.18	–0.19, 0.47	0.53	0, 0.69	0		0.47	0.31, 0.66	range from 0.40 to 0.45 [23] (tension-type headache)
Mixed headache	MZ	0.49	0.36, 0.61	0.45	0.23, 0.57	0		0.55	0.43, 0.67
Mixed headache	DZ	0.12	–0.05, 0.28	0.45	0.23, 0.57	0		0.55	0.43, 0.67
Immunological disorders
Allergic rhinitis	MZ	0.76	0.71, 0.81	0.73	0.55, 0.81	0.04	0, 0.19	0.24	0.19, 0.29	range from 0.33 to 0.91 [24]
Allergic rhinitis	DZ	0.40	0.32, 0.47	0.73	0.55, 0.81	0.04	0, 0.19	0.24	0.19, 0.29	range from 0.33 to 0.91 [24]
Asthma	MZ	0.83	0.80, 0.85	0.68	0.57, 0.79	0.15	0.05, 0.25	0.17	0.15, 0.20	0.54 (95% CI = 0.44, 0.63) [25] (meta-analysis)
Asthma	DZ	0.49	0.44, 0.54	0.68	0.57, 0.79	0.15	0.05, 0.25	0.17	0.15, 0.20	0.54 (95% CI = 0.44, 0.63) [25] (meta-analysis)
Atopic dermatitis	MZ	0.79	0.74, 0.83	0.73	0.55, 0.83	0.06	0, 0.22	0.21	0.20^a, 0.26	0.74 (95% CI = 0.64, 0.83) [25] (meta-analysis)
Atopic dermatitis	DZ	0.43	0.35, 0.50	0.73	0.55, 0.83	0.06	0, 0.22	0.21	0.20^a, 0.26	0.74 (95% CI = 0.64, 0.83) [25] (meta-analysis)
Specific allergy	MZ	0.90	0.85, 0.93	0.71	0.48, 0.93	0.19	0, 0.40	0.10	0.07, 0.14	0.63 (95% CI = 0.55, 0.71) [25] (meta-analysis)
Specific allergy	DZ	0.54	0.42, 0.65	0.71	0.48, 0.93	0.19	0, 0.40	0.10	0.07, 0.14	0.63 (95% CI = 0.55, 0.71) [25] (meta-analysis)
Coeliac disease	MZ	0.96	0.92, 0.98	0.49	0.30, 0.72	0.47	0.24, 0.65	0.04	0.02, 0.08	range from 0.57 to 0.87 [27–29]
Coeliac disease	DZ	0.71	0.60, 0.80	0.49	0.30, 0.72	0.47	0.24, 0.65	0.04	0.02, 0.08	range from 0.57 to 0.87 [27–29]
Gastrointestinal disorders
Constipation	MZ	0.51	0.43, 0.59	0.51	0.30, 0.58	0		0.49	0.43, 0.49^a
Constipation	DZ	0.25	0.17, 0.33	0.51	0.30, 0.58	0		0.49	0.43, 0.49^a
Functional diarrhea	MZ	0.93	0.86, 0.97	0.77	0.42, 0.97	0.16	0, 0.49	0.07	0.03, 0.14
Functional diarrhea	DZ	0.54	0.33, 0.71	0.77	0.42, 0.97	0.16	0, 0.49	0.07	0.03, 0.14
Irritable bowel syndrome	MZ	0.69	0.46, 0.85	0.26	0, 0.83	0.43	0, 0.77	0.31	0.15, 0.53	0.22 (95% CI = 0.13, 0.30) [25] (meta-analysis)
Irritable bowel syndrome	DZ	0.57	0.25, 0.79	0.26	0, 0.83	0.43	0, 0.77	0.31	0.15, 0.53	0.22 (95% CI = 0.13, 0.30) [25] (meta-analysis)
Mixed FGIDs	MZ	0.55	0.48, 0.62	0.56	0.39, 0.62	0		0.44	0.38, 0.51	0.57 (95% CI = 0.41, 0.76) [29]
Mixed FGIDs	DZ	0.27	0.19, 0.34	0.56	0.39, 0.62	0		0.44	0.38, 0.51	0.57 (95% CI = 0.41, 0.76) [29]

The physical health conditions in this study did not include the data from primary care health services

A, additive genetic variance; C, shared environmental variance; DZ, dizygotic twins; E, nonshared environmental variance; FGIDs, functional gastrointestinal disorders; MZ, monozygotic twins; V, phenotypic variance

^aalpha level not reached