The origin of intelligence, is it acquired or is it inherited?

Academic

The origin of intelligence has been a historical debate, is it acquired or is it inherited? Let us just think about the Bohr family. Christian Bohr was a successful physician in Edinburgh, his son, Niehls Bohr, was a Nobel Laureate in Physics, and his grandson, Aage Bohr also won a Nobel Prize in Physics. So, here is the question: Was geniality printed in their genes or did they live in an enriching environment that facilitated their academic achievements?

Nowadays it is hard to deny that academic achievement has become a major goal in society; indeed, academic achievement has been associated to better health, life expectancy and career success. And, as with intelligence, academic achievement appears to depend, at least partially, on the subject’s genetics.

On the other hand, the role of a common environment (family, income, school, educational system, etc) is more difficult to explain. It is an everyday observation that children in the same school, even in the same classroom exhibit higher, or lower, performance that their peers.

An article addressing this question of genetic versus environmental influences on academic achievement has been recently published by a research group from King’s College London (United Kingdom). This large study investigated the academic outcomes of more than 12,000 twins that took their GCSE* (General certificate of Secondary Education – an important test performed at age 16) and analyzed if these outcomes were more related to inheritance or environment.

The results were interesting. The heritability had a correlation of around 54 to 65% with the GCSE outcomes, while environment only had one of 14 to 21%. Heritability had an even greater impact on intelligence, with a correlation of 56%. On the contrary, environment factors were only 5% correlated.

But here is a problem: twins are often raised in the same environment, so to eliminate this factor, the researchers also used a new technique called GCTA (Genome-Wide Complex Trait Analysis). The GCTA is a genetic tool that enables us to study the effect of genetic influence of unrelated individuals**. In this case in academic performance. After the exclusion of 1 out of every twin, a correlation between the genetic similarity of unrelated individuals and the academic performance was addressed again. The new results supported the previous findings in wins, even using the new GCTA technique, a genetic correlation was found in both intelligence and academic achievement in unrelated individuals.

So, it might appear as if all is lost and that our genes will always write our destiny, but do not despair. The researchers explain that the negligible effect of environment may be due to the highly standardized curriculum in the United Kingdom, a country with a strongly centralized educational system. In other studies the effect of environment, health, family, educational system, etc. have proven to be more important when compared with the present study.

Sinapsis MX

* The GCSE evaluates different academic subjects such as mathematics, science, English, art, humanities and second language learning.
** GCTA search for thousands of single nucleotide polymorphisms (SNPs) to calculate the phenotypic variance.

Reference:
Rimfeld K, Kovas Y, Dale PS, Plomin R. Pleiotropy across academic subjects at the end of compulsory education. Sci Rep. 2015 Jul 23;5:11713. doi: 10.1038/srep11713.

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