New research published in social science research Evidence shows that how genetics affect a person’s educational success is highly dependent on the person’s family background, gender, and the country’s school system. By comparing data from four European countries, scientists found that early education tracking tends to reduce the role of genetics in students’ academic performance while increasing the influence of family background.
Scientific interest often focuses on how a family’s socioeconomic status interacts with a child’s genetic characteristics to shape a child’s future. Socioeconomic status refers to a family’s social and economic status, often measured by parents’ education and income levels. Genetic traits such as cognitive abilities and behavioral skills play a natural role in school performance. However, depending on a person’s living environment, the expression of these genetic traits may be restricted or promoted.
Hannu Reti, an academic researcher at the Invest Flagship Center at the University of Turku, led the project to better understand how these two forces interact. “I have always been interested in combining biology and social science, because not only are we human beings social creatures, but our behavior also depends on biological factors,” Letty said. “Behavior is impossible without biology, but the social environment also shapes and modifies it.”
Some past research suggests that children from highly educated families have more resources, which helps them reach their full genetic potential in the classroom. This is known as the enhancement effect. In this scenario, a supportive environment acts as a fertilizer for innate abilities and allows genetic differences to shine.
Other studies suggest the opposite pattern, known as the compensatory effect. In such situations, wealthy and highly educated families utilize extra resources to help their children overcome genetic disadvantages such as learning difficulties and behavioral problems. This additional support ultimately means that the home environment plays a greater role in a child’s academic success, smoothing out natural deficiencies.
To understand these conflicting patterns, the authors of this study wanted to look beyond the immediate family. “My PhD focused on intergenerational education and socio-economic mobility using a sibling design, but because I didn’t have access to twin registries, I couldn’t account for genetic factors,” Lehti explained. “The natural next step was to investigate the relative contributions of genes and environment. I applied for funding to pursue this and received a four-year grant from the Research Council of Finland. This paper was one of the things I planned on that application.”
The scientists suspected that larger societal forces, such as gender expectations and the national school system, also filtered how genetic traits are expressed. “In this study, we wanted to analyze whether institutional differences between countries influence genetic and environmental influences on educational attainment across families and gender,” Letty said.
“We used large twin registers from Finland, Norway, Germany, and the Netherlands and used a nonparametric gene-environment interaction model to analyze gene-environment interactions by parental education and child gender,” Lehti added. Nonparametric models are flexible statistical tools that allow researchers to look for complex patterns in data without making strict a priori assumptions about the shape of relationships.
To test these ideas, scientists analyzed data from identical twins, fraternal twins, and normal siblings from four countries. Identical twins share all of their DNA, while fraternal twins and regular siblings share about half. By comparing how similar educational outcomes are between these different types of siblings, scientists can estimate how much of a given trait is due to genetics, how much is due to a common family environment, and how much is due to unique personal experiences.
The authors collected extensive registration and survey data, primarily among people born between 1980 and 1998. The total sample included exactly 116,772 people from Finland, 271,902 from the Netherlands, 3,958 from Norway, and 3,064 from Germany. The scientists measured educational attainment by calculating the total number of years of schooling each person completed by the time they were in their late 20s or older. They also categorized their parents’ highest level of education as low or high.
This data reveals that the influence of genetics on educational attainment varies by country. Genetic factors had the strongest influence on education in Finland, followed by the Netherlands, Norway and Germany. At the same time, shared family environment had the strongest effect in Germany and the weakest in Finland.
“Although we found no differences between men and women, there were differences between countries, suggesting that educational systems influence heritability, the interaction of genes and environment at the system level,” Professor Reti told SciPost. The authors note that these national differences are consistent with the structure of schools in each country.
In Germany and the Netherlands, students are sorted into different academic courses around the age of 10 or 12. Such systems often require parents to use their own resources to help their children navigate early academic transitions. “Countries with very early educational tracking show that genetic influences are smaller and common environmental influences are larger. This means that twins in these countries, such as Germany, are more similar,” Letty said. Finland and Norway have delayed this academic tracking until age 16, which appears to allow an individual’s genetic ability to play a greater role in a student’s final educational attainment.
The researchers also investigated sex differences in overall genetic influences. They initially expected that genetic effects would be smaller for men than for women, especially in countries with early enrollment tracking. However, the researchers found no significant gender differences in the overall magnitude of genetic or environmental influences on education in any of the four countries.
“A surprising finding was that there were no gender differences in genetic influences within countries, even though men have consistently been shown to have lower educational attainment than women,” Letty said. This suggests that modern generations of men and women have comparable baseline genetic influences when it comes to educational success.
“Men have also been shown to be more sensitive to various social environments, such as family background, but we did not find any significant differences,” Letty explained. “I expected that in Germany, where educational decisions are made earlier than in other countries, men would have a greater influence on the shared environment.”
When researchers looked at how specifically parental education altered these genetic influences, the results became even more complex. Compensatory effects were observed in women from Finland, Norway, and Germany. This means that for women who grew up in highly educated families, the influence of genetics was weaker and the influence of environment was stronger. Highly educated families appear to use their resources to protect their daughters from natural academic disadvantages.
For men, the pattern varies further by country. Compensatory effects for men appeared only in Finland. In Germany, data showed that a common family environment had a particularly strong influence on men from families with less educated parents. This provides evidence that preschool tracking may be particularly difficult for low-achieving boys. The educational outcomes of these boys become more dependent on their family circumstances than on their innate academic ability.
It is important to note that strong genetic influences do not mean doom for biology. “Genes are not deterministic; social structures such as the education system influence heritability,” Letty points out. “The interaction between genes and environment is therefore important. There is no single gene required for education. In fact, there is no such thing as an ‘educational gene.’ Genetic influences on education operate through indirect pathways through other traits, such as cognitive and non-cognitive abilities. ”
As with all research, this study includes some caveats. Sample sizes in Norway and Germany were much smaller than in Finland and the Netherlands. Small samples naturally increase the mathematical uncertainty of statistical estimates. Some of the differences between countries may be influenced not only by the national school system but also by the specific types of data collected.
“We used a twin model that was based on a number of assumptions,” Lehti says. “Most important is the equal environment assumption, that identical and dizygotic twins are treated similarly by their environments. However, although we were not able to test all assumptions with our data, previous studies have noted that this assumption is fairly robust.”
Furthermore, the Finnish and Dutch registries did not contain precise information on whether the twins were monozygotic or dizygotic. Scientists had to estimate this by comparing same-sex siblings with opposite-sex siblings. Future approaches could help address these estimation problems by directly examining a person’s DNA.
“We want to study the traits that mediate genetic influences on education, because it is clear that there is no single gene for educational attainment,” Professor Reti said. “We also hope to move forward in the future by thinking about genetics at a molecular level using polygenic scoring methods.” Polygenic scoring involves analyzing thousands of small genetic variations across a person’s DNA to estimate biological potential for a particular trait, providing a more direct way to study these complex interactions.
The study, “The role of gender in genes through family SES interactions – a twin study across four European countries,” was authored by Hannu Lehti, Kim Stienstra, Tina Baier, and Torkild H. Lyngstad.
