[HTML][HTML] The body-mass index of twins who have been reared apart

AJ Stunkard, JR Harris, NL Pedersen… - New England journal …, 1990 - Mass Medical Soc
AJ Stunkard, JR Harris, NL Pedersen, GE McClearn
New England journal of medicine, 1990Mass Medical Soc
To assess the relative importance of genetic and environmental effects on the body-mass
index (weight in kilograms divided by the square of the height in meters), we studied
samples of identical and fraternal twins, reared apart or reared together. The samples
consisted of 93 pairs of identical twins reared apart, 154 pairs of identical twins reared
together, 218 pairs of fraternal twins reared apart, and 208 pairs of fraternal twins reared
together. The intrapair correlation coefficients of the values for body-mass index of identical …
Abstract
To assess the relative importance of genetic and environmental effects on the body-mass index (weight in kilograms divided by the square of the height in meters), we studied samples of identical and fraternal twins, reared apart or reared together. The samples consisted of 93 pairs of identical twins reared apart, 154 pairs of identical twins reared together, 218 pairs of fraternal twins reared apart, and 208 pairs of fraternal twins reared together.
The intrapair correlation coefficients of the values for body-mass index of identical twins reared apart were 0.70 for men and 0.66 for women. These are the most direct estimates of the relative importance of genetic influences (heritability) on the body-mass index, and they were only slightly lower than those for twins reared together in this and earlier studies. Similar estimates were derived from maximum-likelihood model-fitting analyses — 0.74 for men and 0.69 for women. Nonadditive genetic variance made a significant contribution to the estimates of heritability, particularly among men. Of the potential environmental influences, only those unique to the individual and not those shared by family members were important, contributing about 30 percent of the variance. Sharing the same childhood environment did not contribute to the similarity of the body-mass index of twins later in life.
We conclude that genetic influences on body-mass index are substantial, whereas the childhood environment has little or no influence. These findings corroborate and extend the results of earlier studies of twins and adoptees. (N Engl J Med 1990; 322:1483–7.)
The New England Journal Of Medicine