Gender and genetic contributions to weight identity among adolescents and young adults in the U.S.

In this paper, we investigate the possibility that genetic variation contributes to self-perceived weight status among adolescents and young adults in the U.S. Using samples of identical and fraternal twins across four waves of the National Longitudinal Study of Adolescent to Adult Health (Add Health) study, we calculate heritability estimates for objective body mass index (BMI) that are in line with previous estimates. We also show that perceived weight status is heritable (h² ∼ 0.47) and most importantly that this trait continues to be heritable above and beyond objective BMI (h² ∼ 0.25). We then demonstrate significant sex differences in the heritability of weight identity across the four waves of the study, where h²_women = 0.39, 0.35, 0.40, and 0.50 for each wave, respectively, and h²_men = 0.10, 0.10, 0.23, and 0.03. These results call for a deeper consideration of both identity and gender in genetics research.