The Intelligence Debate: Nature vs. Nurture

Posted by on May 10, 2014 in Featured, Theories | 0 comments

The Intelligence Debate: Nature vs. Nurture

The debate surrounding the heritability of intelligence is one that has been going on for centuries starting with Sir Francis Galton in 1869 and the publication of his book, Hereditary Genius.


Galton was one of the first scientists to study individual differences in intelligence. In his book, Hereditary Genius, he claimed that intelligence is inherited and that this is supported by the fact that eminence runs in families. He went further to say that selective breeding ought to be encouraged in order to improve society which sparked the on-going controversy surrounding eugenics.


While eugenics is not a term people find palatable, Professor Robert Plomin believes that there is some truth in the heritability of intelligence. He argues that there are genetic differences in intelligence and that this is not something to be feared, merely understood. According to twin studies, genetics accounts for approximately 50 percent in individual differences in intelligence.  While facts are facts, many social scientists believe that this notion could have widespread implications regarding equality. After all if we are the product of our genes, are we really all born equal?


Post World War II the very mention of heritability or genetics was considered offensive and crude. As Plomin stated, “If you were interested in studying the genetics of intelligence, you were considered something close to a Nazi.” This ideology favoured the idea that social mobility was possible for everyone and that everyone was born with equal chances in life. It simply depended on their environment as to whether people could flourish or not. This belief was reinforced by the behaviourists who claimed that everything we do and all our knowledge is learnt through the process of conditioning. This was an enticing view as there was always the potential for change, no one was stuck with their genes and anyone could be whatever they wanted to be given the right circumstances. During this time the biological sciences were deemed fatalistic and were seen as trying to impinge on social equality.


While these two views appear to be diametrically opposed, Professor Jill Boucher claims that this need not be the case. Just because genes have an influence on intelligence does not mean that the environment automatically has no impact. As Steven Pinker stated, although twins correlate highly on measures such as intelligence, implicating that intelligence is in the genes, it does not correlate perfectly. There is always some variation which could only be put down to the environment. Therefore, schools, upbringing, prenatal factors can all have an influence on intelligence.


According to Plomin, policies should not be affected in any adversarial way from simply stating the fact that intelligence has a genetic basis. As Pinker stated people seem to want to hope that the blank slate theory is true since it is politically more palatable and seems to offer people more control over their lives. However, denying the facts won’t change them. Genes and environment do not need to be pitted one against the other. They are best seen as working in combination to produce the unique set of traits that make up each individual.



Rutherford, A. (Writer). (April 29, 2014). Born smart. [Radio series episode]. In Buckley, A. (Producer), Intelligence: Born smart, born equal, born different. UK: BBC Radio 4.

Rutherford, A. (Writer). (May 6, 2014). Born equal. [Radio series episode]. In Buckley, A. (Producer), Intelligence: Born smart, born equal, born different. UK: BBC Radio 4.

Image credit: Nature vs. Nurture is no longer the debate. (n.d.). Sciencegymnasium. Retrieved May 10, 2014, from


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