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 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 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.
Kaili Rimfeld, joint-lead author,
also from the IoPPN at King's says: "No policy implications necessarily
follow from finding that genetics differences influence educational
achievement, because policy depends on values and knowledge. However, our
findings support the idea that a more personalized approach to learning may be
more successful than a one size fits all approach. Finding that educational
achievement is heritable certainly does not mean that teachers, parents or
schools aren't important. Education is more than what happens to a child
passively; children are active participants in selecting, modifying, and
creating their experiences -- much of which is linked to their genetic
propensities, known in genetics as genotype-environment correlation."
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