Polygenic Scores and What They Tell Us About the Way Siblings Learn

Polygenic scores tell us how likely it is that a person’s genetic structure is going to support that person’s ability to get an education. In other words, if your child has a high polygenic score, he or she is more likely to go on to get a higher education. Scientists base the polygenic score on what they’ve learned until now about which genomes are linked to getting an education. In other words, through research, scientists know by studying your DNA, whether or not you are likely to go to college.

All of that was just a theory. Until recent times. Now, a nationwide study of siblings has pretty much proven it for sure.

Before this time, researchers looked at unrelated people to try to find the specific genotypes that make people go on to get an education as adults in their mid-20’s to early 30’s. The new study looks at brothers and sisters within families, and finds that a sibling in his or her teens with a higher polygenic score, will complete more years of schooling than his or her sibling with a lower polygenic score.

What does this mean for parents and children? Well, first of all, it means your child’s teacher is onto something when he or she suggests (with either positive or negative overtones) that your child is “Nothing like his brother.” One sibling could be destined by his genetic material to take to schooling like a fish in water, and would thus go on to complete more years of schooling.

Does that mean a child with a lower polygenic score is going to be a high school dropout? Would that child be doomed to do poorly in school, and as a result, not have a successful future? Happily, this is not the case.

For one thing, the sibling with a higher polygenic score, was found to only have around one-third of a year more schooling than his lower scoring brother or sister. Plus, a child’s environment has a great deal to do with his success in school and in life. In fact, one of the more interesting things about genes is epigenetics, which is how culture and environment can change the structure of the DNA we pass on to our children.

But back to the new study on siblings. The study was published in AERA Open, which is the journal of the American Educational Research Association. The research was performed by scientists from Stanford, Duke, U of Colorado, New York U, and the University of North Carolina at Chapel Hill. The data was pulled from the National Longitudinal Study of Adolescent to Adult Health (ADD Health) which includes 1,594 siblings.

Though there was only a slight difference between siblings, and how much education they would attain, based on their polygenic scores, the difference was real and significant. This study helps prove that a child’s genetic makeup really does affect his educational outcome.

Polygenic Scores Within Families

Benjamin Domingue of Stanford University, one of the study authors, said, “By examining siblings, this study was able to control for external social aspects, such as schools, neighborhoods, and level of parental education, to hone in specifically on the role of genes in this complex process. The study provides strong evidence that genotype can predict educational attainment within families.”

But there’s more to be gleaned from this study. The scientists also discovered that not only did a child’s polygenic score make a difference to his academic success, but that his family environment had just as much of an impact on the child’s educational outcomes, though not necessarily in a good way. For instance, two siblings may try to be as different from each other as possible. So if one sibling grows up to become a neuroscientist, for instance, the other sibling might become a truck driver, just to show his independent nature. The researchers, on the other hand, found that birth order had no effect whatsoever, on a sibling’s polygenic score.

What did appear to affect polygenic scores in this study was the society in which these siblings lived. Americans of European heritage who had higher polygenic scores were more likely to live in more “socially advantaged” communities. Their moms had more education, too.

Black Americans’ polygenic scores were not affected by their social environments, but there was a definite link between a mother’s level of education, and a black child’s polygenic score.

“We show, for the first time, clear evidence for socio-geographic patterning of polygenic scores in the contemporary United States,” said Domingue. “Neighborhoods can be important facilitators of, or impediments to, children’s social attainments.”

In summing up their findings, the authors of the study say that there is definitely a link between polygenic scores and the attainment of education. However, in the general population, social factors are still the most significant factors in shaping a child’s academic outcome. How does that work? Well, the authors found that just having a mom who graduated from college, meant that a child would attain an extra 1.7 years of schooling, compared to a child whose mother did not go to college.

Now the researchers caution us that this information about polygenic scores isn’t enough to help us figure out how to help a child with a lower polygenic score improve in school, for instance. But it does tell us we’re on the right track to finding how what makes our children tick in terms of getting an education and succeeding in life. Quite an achievement when you consider that not long ago, we couldn’t even map the human genome.

“Eventually, this type of research will help us better understand, across broad groups, the complex relationship between genetics, environments, and traits and behaviors, as well as help us better understand why school or government policies may or may not be generating desired objectives,” said Domingue.

And that can only be a good thing for our children, going forward.