In this study, we investigated the familial aggregation of body mass index (BMI) in a sample of families with young offspring from eastern Finland. 15-year-olds were examined from 1996 to 1997, and their biological parents were examined from 1993 to 1994. 224 children were invited; 184 families participated, and 144 were included in the analysis with complete data. Significant positive correlations were found for mother-offspring pairs (correlation [r] = 0.31, p