Posts tagged educational achievement
Articles and news from the latest research reports.
Why is educational achievement heritable?
New research, led by King’s College London finds that the high heritability of exam grades reflects many genetically influenced traits such as personality, behaviour problems, and self-efficacy and not just intelligence.
The study, published today in the Proceedings of the National Academy of Sciences (PNAS), looked at 13,306 twins at age 16 who were part of the Medical Research Council (MRC) funded UK Twins Early Development Study (TEDS). The twins were assessed on a range of cognitive and non-cognitive measures, and the researchers had access to their GCSE (General Certificate of Secondary Education) scores.
In total, 83 scales were condensed into nine domains: intelligence, self-efficacy (confidence in one’s own academic ability), personality, well-being, home environment, school environment, health, parent-reported behaviour problems and child reported behaviour problems.
Identical twins share 100% of their genes, and non-identical twins (just as any other siblings) share 50% of the genes that vary between people. Twin pairs share the same environment (family, schools, teachers etc). By comparing identical and non-identical twins, the researchers were able to estimate the relative contributions of genetic and environmental factors. So, if overall, identical twins are more similar on a particular trait than non-identical twins, the differences between the two groups are due to genetics, rather than environment.
Eva Krapohl, joint first author of the study, from the MRC Social, Genetic and Developmental Psychiatry (SGDP) Centre at the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s, says: “Previous work has already established that educational achievement is heritable. In this study, we wanted to find out why that is. What our study shows is that the heritability of educational achievement is much more than just intelligence – it is the combination of many traits which are all heritable to different extents.
“It is important to point out that heritability does not mean that anything is set in stone. It simply means that children differ in how easy and enjoyable they find learning and that much of these differences are influenced by genetics.”
The researchers found that the heritability of GCSE scores was 62%. Individual traits were between 35% and 58% heritable, with intelligence being the most highly heritable. Together, the nine domains accounted for 75% of the heritability of GCSE scores.
Heritability is a population statistic which does not provide any information at an individual level. It describes the extent to which differences between children can be ascribed to DNA differences, on average, in a particular population at a particular time.
(Source: kcl.ac.uk)
Genes Contribute to How Long You Stay in School
There are a variety of factors that determine the number of years a person goes to school – personality, finances, life circumstances, country of origin and social norms. One factor that may be less obvious, however, is genetics. Around 40 percent of the variance in educational attainment can be explained by a person’s DNA, according to previous research. Now a new study is the first to identify specific genes that influence educational achievement.
This research falls under the category of social-science genetics, a topic that includes everything from genes for political affiliation to genes for criminality. Previous studies in the field, however, have found relatively weak associations between specific gene variants and behavior, since behavior is influenced by the accumulation of small effects from many genes.
To counteract that problem, this study was especially large – 125,000 Caucasian people from the United States, Australia, and 13 European countries. Researchers took blood samples and asked participants how many years of schooling they’d completed and whether or not they’d graduated from college. The researchers converted the answers to an international educational standard to allow accurate comparisons between countries.
Then, delving into subjects’ DNA, researchers found three mutations (called SNPs) at specific positions on the genome that were strongly associated with educational outcome – one that corresponded to years of schooling and two that corresponded to college completion. The mutations were found within genes believed to be associated with health, learning, memory and brain-cell mechanics, the researchers report today in Science.
Each mutation contributed only a small amount. In terms of the years of schooling, one copy of the SNP meant that an individual completed 1 month of additional schooling. (Each person can have up to two copies of an individual SNP, one from mom and one from dad.)
For college completion, the most indicative SNP corresponded to a 1.8 percentage-point rise in the likelihood of graduating from college. If a person had two copies of this SNP, then, their likelihood would rise by 3.6 points.
These are small effects but meaningful because they held up on such a large scale. The findings support the general consensus that our behavioral traits are influenced by a large number of genes, each of small effect. Overall, each SNP in this study altered educational attainment by only about 0.02%. In comparison, for a complex physical trait like human height, a single SNP can influence the outcome by 0.4%.
Ongoing genetic research keeps reinforcing this idea that genes aren’t destiny – there’s no gene for graduating college. But it’s good to keep in mind that genes are part of the list of contributors that make us who we are.