Tracing Obesity From Parents to Adult Offspring: The Tromsø Study 1994-2016

The combination of genetic and environmental contributors to obesity can be studied through intergenerational associations as previously shown in studies of parents and their children and adolescents. Few studies have investigated this in adulthood. This study aims to explore sex-specific associations in body mass index (BMI) and obesity status between parents and their adult offspring.

We used cross-sectional data from two surveys in the population-based Tromsø Study. Individuals participating in the seventh (Tromsø7 2015-2016) survey were linked to their parents in the fourth (Tromsø4 1994-1995) survey. Data were analyzed using linear mixed models and generalized estimating equations adjusting for sibling clusters, parents' age and education level, and offspring's sex, age, education, and physical activity level. The analytical sample included 2068 parent-offspring trios, both parents and offspring aged 40-59 years.

Results showed strong associations between parents' and adult offspring's BMI and obesity status, which remained strong after adjustments. Having two parents with obesity (compared to normal weight) showed a 3 times higher risk of obesity in the offspring. Mother-daughter relationships tended to be stronger than mother-son relationships.

Our study adds to previous studies of familial transmission of obesity from parents to their young children and adolescents, confirming these associations persist into middle age.