Education can reduce health differences related to genetic risk of obesity

Abstract

This work investigates whether genetic makeup moderates the effects of education on health. Low statistical power and endogenous measures of environment have been obstacles to the credible estimation of such gene-by-environment interactions. We overcome these obstacles by combining a natural experiment that generated variation in secondary education with polygenic scores for a quarter-million individuals. The additional schooling affected body size, lung function, and blood pressure in middle age. The improvements in body size and lung function were larger for individuals with high genetic predisposition to obesity. As a result, education reduced the gap in unhealthy body size between those in the top and bottom terciles of genetic risk of obesity from 20 to 6 percentage points.

Keywords: education; gene-by-environment; genetics; health; obesity.

Fig. 1.

Health differences by BMI PGS. Bars show means of binary measures of body size (A), lung function (B), blood pressure (C), and summary indices (D) for the bottom, middle, and top terciles of the BMI PGS distribution with 95% confidence intervals. Bars are centered at the median PGS value in the tercile. Sloped lines give linear projection of outcomes on the BMI PGS. R² gives the fraction of the variation in the outcome explained by the BMI PGS. To make estimates comparable to our estimates in Fig. 3, we restricted the sample to participants who were born before September 1, 1957, and who dropped out before age 16 and controlled for a quadratic polynomial in date of birth.

Fig. 2.

Fraction staying in school until age 16 by year of birth for full sample (A), bottom, middle, and top terciles of the BMI PGS distribution (B), and bottom, middle, and top terciles of the EA PGS distribution (C). Dashed vertical lines mark the first birth cohort affected by the raising of the school-leaving age from 15 to 16.

Fig. 3.

Does the effect of staying in school until age 16 depend on the BMI PGS? Bars show 2SLS point estimates of effect of staying in school until age 16 on binary measures of the body size index (A), lung function index (B), blood pressure index (C), and summary index (D) for the bottom, middle, and top terciles of the BMI PGS distribution. Bars are centered at the median PGS value in the tercile. Brackets show 95% confidence intervals. Sloped lines plot β₁PGS_i + β₂. P corresponds to the P value of H₀:β₁ = 0.