Using serial measurements of fatness on the same subjects, and for various age groupings from childhood through later adulthood, continuities and changes in both absolute and relative (age-corrected) fatness will be analyzed, separately at each portion of the leanness-fatness continuum, not only to determine the extent to which the lean remain lean and the obese remain obese, but also the family-line, socioeconomic and other determinants of continuities and changes in fatness both within and between maturity groupings.