Genetic differences between siblings can lead to differences in how far they go in school, according to a new, nationally representative study.
In an article published today in the American Educational Research Association’s open-access journal, researchers from Stanford, Duke, and New York universities, the University of Colorado, Boulder, and the University of North Carolina, Chapel Hill, describe a “polygenic scale” compiled from single-nucleotide polymorphisms—the smallest types of genomic differences—that had all been previously connected to education outcomes.
That’s pretty small, in the grand scheme of things—in the same sample, having a mother with a college degree predicted 1.7 years of additional schooling—but it’s still significant. Moreover, the researchers have so far been able to identify at least one of the reasons for the difference: Those who score higher on the polygenic scale tend to also understand a larger number of words.
“That’s a pretty powerful signal,” said Benjamin W. Domingue, the lead author and an assistant professor at Stanford’s graduate school of education. “The sibling evidence provides strong support that the polygenic score captures something.”
The work confirms and builds on a separate 2013 international study of more than 100,000 unrelated people, which found that about a month’s difference in educational attainment could be traced back to genetic differences.
The current study focused on about 1,600 siblings within the National Longitudinal Study of Adolescent to Adult Health. While this sample was smaller, it allowed researchers to rule out potential differences based on nationality, neighborhoods, parent education levels, and other background characteristics that may separately affect students’ educational attainment.
Still, “the context in which genetics are expressed are incredibly important,” Domingue said. For example, height and weight are strongly heritable, yet, “in one generation we see a massive increase in [body mass index]; that’s not genetics.”
Yet genetic predictions can provide a window to look at the effects of environment. For example, he noted that in the 1950s, when smoking was far more common across all walks of life, genetic differences were less predictive of smoking. As the health effects of smoking have become more well-known and fewer people overall smoke, genetic differences have become more important in predicting nicotine addiction.
Similarly, looking at how genetic differences play out among different groups “gives us a lever to understand how policies affect different people, and places to potentially look for new types of interventions,” Domingue said. “We are very interested in finding whether certain educational environments—certain types of schools or classes—mitigate or exacerbate genetic differences.”
Genetic Findings Need Cautious Use
As University of Virginia psychologist Daniel Willingham has neatly described it, education research often suffers from problems in translating studies at different scales. An individual student’s academic success is affected by changes at many different levels, and, historically, much of education research has focused on those at or above the level of the child: national, state, or district education goals and policies; principal and teacher training and practice; parent and peer support; individual student personality and motivation, and so on. Research focused on smaller scales has exploded in the last decade or so: moment-by-moment student engagement, neurological processes associated with learning grammar or developing dyslexia, and now genetic markers of educational attainment are all blooming.
These new fields can give a new perspective on how students learn, and in some cases fill in gaps in our understanding of problems in education, but it would be inappropriate to try to apply what we learn at the genetic level directly to classroom practice. There will be no practical genetic screenings or reading interventions based on a genetic profile “any time in the foreseeable future,” Domingue said.
It’s still important for educators to be engaged in the conversation around the research, though. Genetics does not have a nice history in the field of education research. Some of the earliest population studies were conducted by avowed eugenicists looking for proof of genetic superiority of whites.
Domingue said he and his colleagues have been particularly sensitive to how the studies will be interpreted and used. He noted that other genetic studies are looking at markers for risk of attention deficits, anxiety, and other factors that may affect a student’s learning.
“There are hints here and there that the genetic architecture of educational attainment will look different from the genetic architecture of say, height, but it’s not something the [education research] has grappled with to any degree,” he said. “In the same way the medical community has had to grapple with [genetic risk factors], we’re going to have to grapple with this, too.”
Video: Single-neucleotide polymorphisms are the smallest levels of genetic differences. Source: YouTube.
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A version of this news article first appeared in the Inside School Research blog.