In 2013, Angelina Jolie brought attention to genetics when she announced that she had had a double mastectomy. A gene mutation had increased her risk of breast cancer to 87 percent, so she preemptively removed the potentially cancerous tissue.
Researchers are finding more and more associations with particular sets of genes, from cancer and obesity risks to how far you’ll go in school. A recent study from Duke, UNC and other universities, published in the Proceedings of the National Academy of Sciences, confirmed that a genetic “score” predicted how far people went in school, how far they advanced in their careers and how much wealth they accumulated.
If you’re skeptical of linking genes to success, you’re not alone. But lead author Dan Belsky of Duke University thinks that studying genetic associations can help the push for equality.
“We accept that it’s not anybody’s fault if you happen to be born with a genetic mutation that gives you extra risk for cancer, but when we talk about non-health characteristics that logic falls apart,” Belsky said. “[This work] could change the debate around inequality and promote the idea that achieving success in life depends on a lot of things, many of which are beyond your control.”
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How to calculate a genetic score
Our DNA is a city of genetic information spread over 23 pairs of neighborhoods, called chromosomes. Each neighborhood contains hundreds of millions of addresses. Of the 3.3 billion houses in our cities, almost all hold normal occupants.
But a few of those houses vary. At any given location, a person can have zero, one or two variants — two if matching addresses in a pair of chromosomes both hold variants.
To make a genetic score for a particular trait like obesity, researchers scour the cities of obese and not-obese people to figure out which addresses show a difference. They combine how many variants a person has in those particular houses to form the score.
This new study tests a score built from a 2016 paper that identified the genetic addresses associated with finishing more school in people of European ancestry. The 2016 paper suggested that genetics accounts for 11 percent of a person’s educational success.
“There was skepticism about whether you could find a genetic marker that would predict educational attainment,” said Kevin Thom, professor at the University of Toronto, who co-authored the 2016 paper and explained genetic addresses to us. “Education is complicated, and it’s the outcome of environmental factors, decisions you make along the way, and attributes and abilities and characteristics of an individual person.
“But we’ve been able to find markers that predict educational attainment, and our studies have been the basis for constructing these [scores] that have shown remarkable level of predictive power.”
Exact addresses differ across ancestries, so this data can’t be applied to people of other ethnic backgrounds. For instance, when researchers tried to use a height score derived from European data, they predicted that West Africans would be shorter than average Europeans. It didn’t work.
What this study found
Belsky and his co-authors computed the educational attainment score of more than 20,000 people who had participated in five long-term studies in the U.S., the U.K. and New Zealand. One study followed the career paths of 7,000 Wisconsinites from their 1957 high school graduation until 2011, when most of them had retired.
For the Wisconsin study, the scientists compared scores against the retirees’ wealth. Kids who start life with more money have an advantage here, so instead of only looking at wealth, the researchers focused on whether the adults had moved up or down the economic ladder, their social mobility.
“It’s important to disentangle genetic effects on development from simply being born lucky and being born into a wealthier family,” Belsky said.
To get around the advantage wealthier kids had, Belsky and his co-authors also computed scores for fraternal twins, who have different genes but grow up in the same environment with the same parents. They compared high school graduation rates of 930 pairs of twin boys born in England in 1994.
“Even when you look at siblings with the same parents, same environment, same social background, this score still predicts differences in the outcomes,” said Thom, who was not involved in the new study. “The within-family analysis convinces me that this isn’t just a story about more privileged family backgrounds.”
In all five studies, the researchers found that the higher your genetic score, the better you did in life, whether that meant school, work or wealth. The effect stayed no matter what social class you were born into. But it was small, said Kathleen Mullan Harris, professor at UNC and another author of the study.
“The genes explain less than 5 percent of the variation in social mobility,” Harris said. “Of course genes matter, but guess what, the environment probably matters more.”
Harris leads one of the five long-term studies,which is following over 5,000 Americans who were teenagers in 1994.
The researchers also found that your mother’s score influences your success. It’s not all nature or all nurture — the two are deeply intertwined.
“One of the reasons these genetics are associated with this kind of success in life is because they’re associated with something in the family environment that helps kids get ahead,” Belsky said.
“It’s possible that these genetics have nothing to do with education or success. They don’t make people smarter or better at delayed gratification or planning. It might be that they encourage the kind of parenting that benefits kids when it comes to their educational success.”
Evening the score
Belsky wants social scientists to take genetics research like this into account when thinking about how to level the playing field.
“The goal of our research is to use genetics to better understand how human attainment is achieved, and ultimately helping find interventions on our environment than help everyone reach success,” Belsky said.
“If it turns out these kids do better in school because they have parents who expose them earlier to more intellectual stimulation or challenge them in particular ways, then we can think of practices to promote this kind of parenting.”