Brandkvist M, et al. - Via a longitudinal study of 118,959 individuals aged 13-80 years recruited from the general population of Norway, experts examined the trajectories of body mass index (BMI) among study participants over five decades, and assessed the differential impact of the obesogenic environment on BMI according to genetic predilection. Starting between the mid-1980s and mid-1990s, obesity expanded in Norway and, in contrast with older birth cohorts, those born after 1970 had a considerably greater BMI already in young adulthood. Among the highest and lowest fifths of genetic susceptibility for all ages at each decade, a substantial difference in BMI was seen—which steadily elevated from the 1960s to the 2000s. The most genetically predisposed had 1.20 kg/m² greater BMI than those who were scarcely genetically predisposed in the 1960s in comparison with 2.09 kg/m² in the 2000s, for 35-year-old men. The corresponding variations in BMI for women of the same age were 1.77 kg/m² and 2.58 kg/m². Hence, genetically predisposed people were observed at greater risk for higher BMI and genetic predisposition communicated with the obesogenic environment that led to higher BMI, as seen between the mid-1980s and mid-2000s. Moreover, elevation in the BMI was identified for both genetically predisposed and non-predisposed people, suggesting that the environment remains the chief contributor.