A USC Dornsife study finds that together, genetics and years of education can influence whether someone becomes obese
In 1972, England, Scotland and Wales raised the mandatory school attendance age from 15 to 16. Through a large-scale genetic study, USC Dornsife researchers have found that decades later, the change had a health benefit for those students affected by the reform, especially those who were at greatest risk of becoming obese.
The extra year of education contributed to weight loss, despite their genetic risk, the research team found.
“This means that genes alone do not determine who will become obese,” said Silvia H. Barcellos, a research scientist at USC Dornsife’s Center for Economic and Social Research (CESR). “In fact in this case, one more year of high school lowered the influence of genes on whether someone becomes obese.”
Before the mandatory attendance age was changed, 31 out of every 100 people with the highest genetic-risk had an unhealthy body size. After the reform, the rate dropped to 18 out of every 100.
Among those with the lowest risk, the rate remained roughly unchanged.
The latest findings were published today by the journal Proceedings of the National Academy of Sciences.
The study is the latest in a series by the USC Dornsife CESR researchers that examines how the 1972 change in the mandatory attendance age has affected other life outcomes for the affected students, such as whether they went to college or completed advance degrees, what incomes they earned and their socioeconomic status.
Those at greatest risk benefit the most
For this study, USC Dornsife researchers studied the genomes of 250,000 people in the UK Biobank.
The researchers looked at three health indicators: lung function, blood pressure and a “body size index.” This index accounted for BMI (body mass index), body fat percentage and waist-to-hip ratio, as comprehensive indicators for healthy and unhealthy weight.
The scientists combined the health information with polygenic scores — a tool that accounts for variation across a person’s entire genome — to determine how much influence genetics and education may have on health.