It is likely that variations within candidate genes may have a differential impact on individuals based on their genetic background. It is also probable that body composition is influenced by many genes, often within the same metabolic pathways, with small individual effects. These genes may not be significantly associated individually, but when examined as a unit (in a candidate pathway or gene-gene interaction framework) the association becomes significant. Further, children's early environmental exposures (e.g. diet) may interact with both genetic background and variations in candidate genes along resulting in alterations in body composition that predispose HA to excess fat accumulation throughout the lifecourse. To that end, the following specific aims will be evaluated: