GENETIC INFLUENCES ON DAILY INTAKE AND MEAL PATTERNS OF HUMANS

The heritability of nutrient intake was investigated with 109 identica l and 86 fraternal adult twin pairs who were paid to maintain 7-day fo od intake diaries. Both classical analysis of heritability and linear structural modeling revealed significant additive genetic influences o n body size, height and weight, and body fatness (body-mass index). Si gnificant heritabilities were also found for the amount of food energy ingested daily, as well as its macronutrient, alcohol, and water cont ent. Linear structural modeling analysis showed that 65% of the varian ce in energy intake was attributable to heredity. In addition, the pat tern of intake, meal frequency, size, and meal macronutrient, alcohol, and water composition, were also found to have strong heritabilities. Linear structural modeling indicated that 44% of the variance in meal frequency and 65% of the variance in meal size was attributable to he redity. However, shared, familial environment had no significant impac t on the levels or pattern of intake in adulthood. These results indic ate that not only body size but also the pattern and amounts of nutrie nts ingested by humans in natural environments are strongly influenced by the immediate environment and heredity, but not at all by the fami lial environment.