title: Education modifies genetic and environmental influences on BMI.
abstract: Obesity is more common among the less educated, suggesting education-related environmental triggers. Such triggers may act differently dependent on genetic and environmental predisposition to obesity. In a Danish Twin Registry survey, 21,522 twins of same-sex pairs provided zygosity, height, weight, and education data. Body mass index (BMI = kg weight/ m height(2)) was used to measure degree of obesity. We used quantitative genetic modeling to examine how genetic and shared and nonshared environmental variance in BMI differed by level of education and to estimate how genetic and shared and nonshared environmental correlations between education and BMI differed by level of education, analyzing women and men separately. Correlations between education and BMI were -.13 in women, -.15 in men. High BMI's were less frequent among well-educated participants, generating less variance. In women, this was due to restriction of all forms of variance, overall by a factor of about 2. In men, genetic variance did not vary with education, but results for shared and nonshared environmental variance were similar to those for women. The contributions of the shared environment to the correlations between education and BMI were substantial among the well-educated, suggesting importance of familial environmental influences common to high education and lower BMI. Family influence was particularly important in linking high education and lower levels of obesity.
authors.affiliation: Centre for Cognitive Ageing and Cognitive Epidemiology, Department of Psychology, University of Edinburgh, Edinburgh, United Kingdom. wendy.johnson@ed.ac.uk
authors.forename: Wendy
authors.initials: W
authors.lastname: Johnson
authors.forename: Kirsten Ohm
authors.initials: KO
authors.lastname: Kyvik
authors.forename: Axel
authors.initials: A
authors.lastname: Skytthe
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Deary
authors.forename: Thorkild I A
authors.initials: TI
authors.lastname: Sørensen
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D004522:Educational Status; D004777:Environment; D005260:Female; D014644:Genetic Variation; D006801:Humans; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D014427:Twins; D055815:Young Adult