The worldwide prevalence of obesity has tripled since 1975, and nearly a third of the world's population is now classified as overweight or obese. This rising prevalence of obesity is not only due to single genetic or environmental factors, but largely attributed to complex gene-environment interactions. Genetically predisposed individuals may be more prone to obesity in an obesogenic environment. Previous studies have focused on the identification of specific environmental factors that interact with genetic predisposition to obesity. The results indicate that physical activity, diet, age, gender and ethnicity could modulate the risk for obesity. Socioeconomic position (SEP) is relevant to all realms of behaviors and lifestyles, is a key factor that determines health across the lifespan, and may carry over to subsequent generations. The fact that BMI inequalities have persisted across different generations means that SEP is a significant factor to consider when understanding the role of environment. Parental SEP could influence the offspring’s risk of obesity through shared lifestyles such as dietary profile, home environment, social networks, and physical activity patterns early in life, which may be exacerbated by predisposition to obesity. Emerging studies have started to focus on SEP mobility across the life course, or intergenerational SEP mobility across two generations. The findings show evidence that higher parental education may be favorable in lowering obesity risk in offspring, especially for women. Longitudinal research should minimize reverse causation and allow us to investigate the dynamic interplay between one’s social strata of origin and own achieved social strata on obesity. However, it is still unclear how early the ancestors’ influence emerge and to what extent susceptibility to obesity is attenuated by SEP mobility.
We hypothesize that higher grandparental SEP, and upward SEP mobility across generations would diminish the grandchildren’s risk of obesity, compared to those who are always in social disadvantaged strata. The approach to consider ancestors’ SEP as a modifier in the heritability of BMI will add in tailoring appropriate interventions in future work.