Table 3

Regression coefficients (β) and 95% CIs for offspring body mass index (BMI) regressed on mid-parental BMI to estimate heritability (h²) using linear mixed effects model with maximum likelihood

	Sons					Daughters
	n	Mean (SD)	h²	95% CI	p Value	n	Mean (SD)	h²	95% CI	p Value
Offspring of all parents	1025	26.5 (4.0)	0.509	0.424 to 0.594	<0.001	1266	25.9 (5.0)	0.555	0.461 to 0.649	<0.001
Offspring with two lean parents (BMI <25 kg/m²)	201	24.7 (3.7)	0.555	0.148 to 0.963	0.008	244	24.3 (4.5)	0.986	0.523 to 1.449	<0.001
Offspring with overweight/obese fathers (BMI ≥25 kg/m²) and lean mothers (BMI <25 kg/m²)	270^a	26.4 (3.5)	0.453	0.130 to 0.777	0.006	316	25.1 (4.3)	0.795	0.431 to 1.159	<0.001
Offspring with overweight/obese mothers (BMI ≥25 kg/m²) and lean fathers (BMI <25 kg/m²)	178^b	25.9 (3.4)	0.492	0.198 to 0.786	0.001	225	26.0 (5.0)	0.352	0.041 to 0.662	0.027
Offspring with one overweight/obese parent (BMI ≥25 kg/m²)	448*	26.2 (3.5)	0.473	0.254 to 0.693	<0.001	541	25.5 (4.6)	0.481	0.242 to 0.721	<0.001
Offspring with two overweight/obese parents (BMI ≥25 kg/m²)	374	27.9 (1.5)	0.487	0.294 to 0.681	0.001	495	27.1 (5.2)	0.719	0.508 to 0.931	<0.001
Offspring with at least one obese parent (BMI ≥30 kg/m²)	234	31.4 (4.8)	0.391	0.162 to 0.620	0.001	303	31.3 (5.4)	0.755	0.512 to 0.998	<0.001

Data were adjusted for family clustering, parental and offspring age, smoking status and social class. Data were analysed for offspring with parents of all BMI values and for six separate groups of offspring, without obese parents or those with at least one obese parent.
*Total of a+b.