Grandparents' educational attainment is associated with grandchildren's epigenetic-based age acceleration in the National Growth and Health Study.

We examined three generations (grandparents, mothers, and grandchildren) to assess the association between grandparents' educational attainment and their grandchildren's epigenetic-based age acceleration and whether the association was mediated by parental educational attainment and mothers' life course health-related factors. Mothers were recruited to the NHLBI Growth and Health Study at 9-10 years and followed for 10 years (1987-1998). Mothers were then re-contacted three decades later (ages 37-42) to participate in the National Growth and Health Study (NGHS), and health information from their youngest child (i.e., grandchildren; N = 241, ages 2-17) was collected, including their saliva samples to calculate epigenetic age. Five epigenetic-based age acceleration measures were included in this analysis, including four epigenetic clock age accelerations (Horvath, Hannum, GrimAge, and PhenoAge) and DunedinPACE. Grandparents reported their highest education during the initial enrollment interviews. Parental educational attainment and mothers' life course health-related factors (childhood BMI trajectories, adult cardiovascular health behavioral risk score, and adult c-reactive protein) are included as mediators. Grandparents' education was significantly associated with Horvath age acceleration (b = -0.32, SE = 0.14, p = 0.021). Grandchildren with college-degree grandparents showed significantly slower Horvath age accelerations than those without college degrees. This association was partially mediated by parental education and mothers' health-related factors, especially adult cardiovascular health behavioral risk score and CRP, but not mothers' childhood BMI trajectory. This ability to conserve the speed of biological aging may have considerable consequences in shaping health trajectories across the lifespan.