Family resemblance in energy and macronutrient intakes: the Stanislas Family Study.

BACKGROUND There seems to be a consensus that family influences on dietary habits are important but few studies have addressed this issue directly. The purpose of this study was to determine if and how dietary intake aggregates within families. METHODS We examined the family aggregation of energy intake and the proportion of protein, fat and carbohydrate in the diet, estimated by a 3-day food consumption diary in 387 middle-class French families. RESULTS For energy and all macronutrients, spouse-spouse and child-child correlations were higher than parent-child correlations suggesting the minor contribution of genetics and the preponderant role of cultural and residual random environment. Variance component analysis confirmed the absence of genetic component for energy and all macronutrients and underlined the important role of a cohabitational effect for parents. Cultural inheritance represented 30-40% of dietary intake variance for children. Families who shared meals together more often had a lower residual random component. With the increasing number of meals eaten together (> 45/week versus < or = 45/week), between-generation components increased by about 10% for fat and carbohydrate, while for protein intake, the between-generation component for both parents (about 27%) and children (about 37%) remained unchanged. CONCLUSIONS The general finding that dietary intake aggregates within families and that the individual behaviours are greatly influenced by characteristics within the family unit such as the number of meals eaten together provides additional justification for health promotion programmes that target the family as the unit for intervention.