Nature and Nurture in Early Feeding Behavior.

Obesity has reached epidemic proportions and research into its prevention is increasingly focusing on the earliest stages of life. Avidity of appetite has been linked to a higher risk of obesity, but studies in infancy were scarce. The Gemini twin cohort was established to investigate genetic and environmental determinants of weight trajectories in early childhood with a focus on appetite and the home environment. Gemini families have been supplying questionnaire data at regular intervals, starting when the twins were 8 months old. Analyses of data on infant appetite and weight have provided a number of important findings. Firstly, a prospective study found that appetite in infancy drives weight gain more strongly than weight drives appetite, although the two processes do coexist. A further study using a subsample of twins discordant for appetite ruled out the possibility of familial confounding, suggesting a causal role for appetite in weight. Heritability estimates for appetitive traits were moderate to high (53-84%). Finally, multivariate analyses indicated that roughly one third of the genes related to weight are also related to appetite and vice versa. Environmental factors affecting appetite in infancy are understudied, but some potential strategies for minimizing over- or underconsumption by at-risk individuals are suggested.