report by Rokholm and colleagues (2011). These researchers used measured height and weight from nearly 4,000 twin pairs from the Swedish Twin Register born between 1951 and 1985. They showed a steady increase in the contribution of genetic factors to variation in BMI for each successive birth cohort; the additive genetic variance for BMI was 4.3 (4.1, 4.5) for the earliest cohort, and 7.9 (7.3, 8.5) for the most recent cohort. They concluded that “the obesogenic environment has enhanced the influence of adiposity related genes” (p. 1).
