Lean legacy, heavy heritage: family history of diabetes and its association with young adult body mass index.

Substantial intergenerational transmission of diabetes mellitus (DM) risk exists. However, less is known regarding whether parental DM and DM among extended family members relate to adult offspring's body mass index (BMI), and whether any of these associations vary by sex. Using data from the National Longitudinal Study of Youth 1997 cohort (NLSY97), we assess the sex-specific relationship between DM present in first-degree parents and second-degree relatives and BMI among the parents' young adult offspring.Multivariate regressions reveal a positive relationship between parental DM and young adults' BMI for both daughters and sons, and the magnitude of coefficients is somewhat larger for the same-sex parent. Further, we observe that the link between parental DM and young adults' BMI is strongest when both parents have diagnosed diabetes. In contrast, the relationship between second-degree relatives with DM and the respondent's BMI is weaker and appears to be sex-specific, through same-sex parent and respondent. Logistic regressions show the association is especially strong when assessing how parental DM status relates to young adults' obesity risk. These results generally persist when controlling for parental BMI. The findings of this study point to the need to better distinguish the role of shared family environments (e.g., eating and physical activity patterns) from shared genes in order to understand factors that may influence young adults' BMI. Young adult offspring of parents with diabetes should be targeted for obesity prevention efforts in order to reduce their risks of obesity and perhaps diabetes.