We've known for a while that your affluence affects your height and weight. For instance, people from poorer backgrounds tend to be shorter and have a higher BMI, in part because their education and nutrition in childhood and early adulthood lacks in comparison to those with more wealth.
Scientists at the University of Exeter wanted to know whether the association could go the other way around. Could being a bit shorter or a bit fatter influence your opportunities in life, as measured by income and other socioeconomic factors?
The research team analyzed the data of 120,286 white British adults between the ages of 40 and 70. All were registered in the UK Biobank. The researchers did not include other ethnicities because minorities have it harder from the start.
The scientists used Mendelian randomization, a method used in epidemiology to measure a causal effect from observational data. They looked at 400 genetic variants linked with height and 70 genetic variants linked with BMI. Socioeconomic status was evaluated through five measures: academic degree level, length of full-time education, job class, annual household income, and the Townsend deprivation index, which is a recognized measure of material deprivation that looks at unemployment, whether a person owns a car or home, and household overcrowding.
"The genetic analysis we used is the best possible method to test this link outside of randomly altering people's height and weight for a study, which is obviously impossible,” lead study author Jess Tyrrell said in a press release. The used method “is not subjective to reverse causality, so we can really use it to try to work out whether height or BMI have a causal role in socioeconomic status,” Tyrell said in a video provided by The BMJ.
The data found that being a shorter man or a heavier woman leads to lower chances in life in areas such as education, occupation, and income.
To illustrate what this means: “If you could take the same woman, same intellect, same CV, but send her through life a stone heavier, she would be about 1,500 pounds per year worse off,” said molecular geneticist Timothy Frayling, leader of the research team.
“If you could take the same man, say a 5’10” man, but make him 5’7” and send him through life, he would be about 1,500 pounds worse off per year.“
Of the measures taken into consideration, a woman’s BMI has the largest effect on her income and deprivation score. A man’s height has the largest effect on his education, income, and job class. Of course, there are exceptions to this finding.
“Science must now ask, why are we seeing this pattern?” says Frayling in the video. “Is this down to factors such low self-esteem or depression, or [does] it [have] more to do with discrimination?… In a world where we are obsessed with body image, are employers biased? That would be bad both for the individuals involved and for society.”
The findings were published on March 8, 2016, in the open access journal The BMJ.
Sources: The BMJ, University of Exeter press release via EurekAlert!, BMJ press release via EurekAlert!, Video provided by The BMJ