30 November 2016
Several studies have found that higher levels of education and financial security tend to be linked to increased height and lower body mass index (BMI)—presumably due to a more nutritious diet and a healthier overall lifestyle. However, recent findings from molecular geneticist Timothy Frayling, from the Royal Devon and Exeter Hospital in the UK, and colleagues suggest that an individual’s socioeconomic status can be affected by innate differences in weight and stature.
Although higher standards of nutrition in childhood have a bearing on height and BMI, both traits also have well-established hereditary components. Indeed, researchers have identified numerous genetic markers that seem to directly affect these physical characteristics. Frayling and colleagues took advantage of the UK Biobank, a massive repository of biological specimens and biomedical data from more than half a million individuals. Based on a sample of roughly 120,000 UK Biobank contributors, they hoped to determine the extent to which differences in career, educational and economic achievement might be an effect rather than a cause of physical differences.
In keeping with past results, individuals who were taller and exhibited a lower BMI tended to fare better from a socioeconomic standpoint. These individuals generally received more education, earned more money, and were more likely to hold down skilled jobs. This pattern generally held true for men and women.
However, interesting causal patterns began to emerge when genetic data were taken into account. Among men, a genetic predisposition to shorter stature appears to be a predictor of reduced educational and career success. For example, a genetically associated height difference of 6.3 centimetres above the average height was associated with a considerably higher likelihood of working in a skilled profession, and this height difference also correlated with a £1,580 increase in household income.
This height-related pattern was not observed among women, but female subjects with higher BMI appear to suffer equivalent setbacks in the working world. Women who were relatively heavier as a consequence of genetic factors generally took a hit in their earnings — an increase of 4.6kg/m2 in BMI was associated with a £2,940 drop in household income. These women were also more likely to experience other indicators of socioeconomic deprivation, such as unemployment, lack of a car or overcrowding in their home.
For both men and women, these differences are likely to represent the consequences of social discrimination. Given that many societies consider taller men to be stronger and better leaders and thinner women to be more attractive, genetic determinants of these traits could have profound impacts on an individual’s success and long-term well-being.
Tyrrell, J., Jones, S.E., Beaumont, R., Astley, C.M., Lovell, R. et al. Height, body mass index, and socioeconomic status: mendelian randomisation study in UK Biobank. BMJ (2016).| article