Several twin studies have been performed to estimate heritability of the BMI, some of which have encompassed over 1000 twin pairs. The results have been very consistent: The intrapair correlations among monozygotic twins were typically between 0.6 and 0.8 independent of age and gender. In one study the correlations for monozygotic and dizygotic twins were basically the same independent of whether the twins had been reared apart or together. Heritability of the BMI was estimated at 0.7; non-shared environmental factors explained the remaining 30% of the variance. Unexpectedly, shared environmental factors did not explain a substantial proportion of the variance.
Pietilaninen KH et al., Int J Obs RElat Metab Disord. 1999; 23:107-115
