A study with 6,653 pairs of twins reveals that differences scholastic achievement levels are linked to many genetically influenced traits. Not only is intelligence highly heritable, but so are motivation, confidence in your own abilities, and dozens more -- further confirming that grades and exam scores are based on many inherited traits, and not just IQ alone. The work was published Proceedings of the National Academy of Sciences this week.
How well a child does in school is typically considered a result of environmental influences ranging from classroom setting to parents’ involvement. Recent work have shown that academic achievement may be heritable. “In this study, we wanted to find out why that is,” says Eva Krapohl of King's College London.
To investigate whether educational achievement is due to heritable traits, Krapohl and colleagues reviewed standardized exam scores of 13,306 twins. The General Certificate of Secondary Education (GCSE) is a UK-wide test compulsory for 16-year-olds, and it assesses performance in subjects like math, science, and English. The researchers also evaluated the teenagers for 83 measures of psychological traits from nine broad categories: intelligence, personality, self-efficacy, well-being, home environment, school environment, health, and both parent-reported and self-reported behavioral problems.
The test group included identical twins and non-identical twins (who are 50 percent genetically similar), and the team assumed both twin types were exposed to the same home and school environments. By comparing the two types of twins, they hoped to identify the relative contribution of environmental factors and genetic inheritance.
The team found that 62 percent of educational achievement (on that exam at least) was due to genetic factors. Of the 83 individual traits they looked at, between 35 and 58 percent were heritable. Intelligence was the most highly heritable of them, and altogether, these traits accounted for 75 percent of the heritability of GCSE performance.
“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,” Krapohl explains in a news release. “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.”