Birth weight has been shown to be associated with obesity and metabolic diseases in adulthood, however, the genetic contribution is still controversial. The objective of this analysis is to explore the genetic contribution to the relationship between birth weight and later risk for obesity and metabolic diseases in Hispanic children. Subjects were 1,030 Hispanic children in the Viva La Familia Study. Phenotypes included body size, body composition, blood pressure, fasting glucose, insulin, lipids, and liver enzymes. Birth weights were obtained from Texas birth certificates. Quantitative genetic analyses were conducted using SOLAR software. Birth weight was highly heritable, as were all other phenotypes. Phenotypically, birth weight was positively correlated to childhood body size parameters. Decomposition of these phenotypic correlations into genetic and environmental components revealed significant genetic correlations, ranging from 0.30 to 0.59. Negative genetic correlations were seen between birth weight and lipids. The genome scan of birth weight mapped to a region near marker D10S537 (LOD = 2.6). The bivariate genome-wide scan of birth weight and childhood weight or total cholesterol, improved the LOD score to 3.09 and 2.85, respectively. Chromosome 10q22 harbors genes influencing both birth weight and childhood body size and cardiovascular disease risk in Hispanic children.