This phenomenon has been documented in the past, but earlier studies used mostly observational data. What's different about this study is that it looks at a person's genetic predisposition for height and weight.
That means there are no broader environmental factors at play here. Poorer people, on average,
tend to have poorer childhood nutrition
, which can stunt growth and may lead to obesity. But there may be more to it.
The authors came to this conclusion looking at the genetic data of 119,669 women and men of white British ancestry, between the ages of 37 and 73, who are a part of the UK Biobank
, a large group of people who have volunteered to be studied for the sake of science.
Looking at the genetic variants that suggest the person would be tall or short, regardless of nutrition or environment, the men with the genes that will likely lead them to be tall, have about £2,940 (about $4,175) higher annual household income. The correlation was about 50% stronger in men. Short women are in luck. There was no real household income difference between short and tall women.
For women, where the income difference did show up was with their weight. Women with genes that will predispose them to have a higher BMI had annual household incomes that were about £1,890 less (about $2,684). Interestingly, with the men, genes for carrying more weight didn't seem to much influence their salary.
The authors did find common challenges that could lead both people genetically predisposed to be shorter and heavier to earn less, regardless of gender. People with genetic variants for higher BMIs tended to leave school earlier than people with the genes associated with being thinner.
People with the genes for heaviness tended to work more in less-skilled professions. People with the tall genes -- both men and women -- tended to stay in school longer and earn higher degrees and they typically worked more in professional positions than in unskilled labor jobs.
Using genes to look at this issue gives less room for observational bias, the authors argue. "That's why we think this is such a good test," said co-author Timothy Frayling
, a professor of molecular genetics at the University of Exeter Medical School.
Earlier studies showed similar results
. Short men do tend to get the, well, short end of the stick, as do overweight women. Taller men get hired or promoted more
into business leadership roles, some studies have shown. For example, the average height
of a Fortune 500 CEO
is 6 feet tall. Short men rarely become president.
The average height of all U.S. presidents is 5 feet 11 inches tall (average height for men
in the United States is a little over 5 feet 9 and a half inches). And short men seem to need a lot more positive attributes compared to tall men if they want to get picked for dating. A Duke University study showed for every inch below 5 feet 10 inches tall, a man has to earn $30,000 more to be seen as equally appealing to women in the dating market, which may be a rare man indeed if this current study is true.
Heavier women also tend to get picked for promotions or open jobs less often, and date less, according to earlier studies.
While this latest study specifically looks at white people in the UK, Frayling suspects if his team was to run the numbers in the United States "it would be similar results." Missing from this sample is racial diversity and information about the younger generation.
Frayling hopes that future scientists will "pick up the baton and investigate the causes and links that lead to these outcomes."
Could the earnings differences be because of depression or a lack of confidence among shorter or heavier people, as some earlier studies have theorized? Economists will want to know as they try to understand the obesity epidemic and its potential impact on productivity.