Genetic and environmental effects on body mass index during adolescence: a prospective study among Finnish twins

Objective: To study genetic and environmental factors affecting body mass index (BMI) and BMI phenotypic correlations across adolescence. Design: Prospective, population-based, twin cohort study. Participants and methods: We used twin modeling in 2413 monozygotic and same-sex and opposite-sex dizygotic Finnish twin pairs born in 1983–1987 and assessed using self-report questionnaires at 11–12, 14 and 17 years of age. Results: Heritability of BMI was estimated to be 0.58–0.69 among 11–12- and 14-year-old boys and girls, 0.83 among 17-year-old boys and 0.74 among 17-year-old girls. Common environmental effects shared by siblings were 0.15–0.24 among 11–12- and 14-year-old boys and girls but n…