The aims of this descriptive study in nuclear families were: 1) assess the distribution of nutritional stage of parents with respect to the nutritional stage of their children and 2) analyze those parents with the highest frequency of children at risk of being overweight (RS) and overweight (S). Body mass index (BMI) was determined in a sample of 126 nuclear families. Kappa values for parents and children were 0.95 and 0.97, respectively. For parents, birthplace of four grandparents was known. A wide variability in the nutritional stage (assessed by BMI) of the 252 parents (Normal-Normal, Normal-Obese, etc.) and their 300 children (Undernourished, Normal, RS and S) was found. A minimum number of children with RS and S (7.7%) was found among parents with Normal-Normal nutritional stage (reference group) in comparison with children whose parents were Overweight-Overweight (22%) and Overweight-Obese (35%). Since we found in parents Overweight-Overweight and Overweight-Obese a greater proportion of children with RS and S, this finding will facilitate the search for susceptibility genes for obesity in Mexican nuclear families with these characteristics.