Intelligence: Genes… the Sharpest Tool in the Shed?

Have you heard about the Imafidon family? Chris and Ann Imafidon and their five children, a Nigerian family living in the UK, are known as the smartest family in England. Chris, a multi-award winning scientist; twins, Paula and Peter, the youngest children in British history to attend high school and pass the University of Cambridge’s advanced mathematics exam; Ann-Marie, the youngest person ever to graduate with a master’s degree, at age 19, from Oxford; Christina, the youngest person to be accepted onto a degree course at age 11; and finally, Samantha, who passed two high school-level mathematics and statistics exams at the age of 6. An undeniably very smart family, which automatically leads to questions on how they are all so intelligent. Could it be their upbringing? Their education? Or could it be their genes?

Studying intelligence has always been incredibly challenging, because of its complexity; there is not only one factor which can impact intelligence, and separating these factors is next to impossible. Also, intelligence has been defined and measured in many ways, making it more difficult to pin down what exactly it is. Generally, intelligence is defined as an ability to learn from experience and adapt to changing environments, by reasoning, planning, problem solving etc. It’s often measured using the intelligence quotient (IQ), and many studies examining the genetic influence on intelligence use IQ as a measure.

Twin studies are often a good way to test whether genetics is playing a role in a particular trait; researchers compare how often specific traits occur in identical twins, who share 100% of their DNA, compared to non-identical twins, who only share 50% of their DNA (the same amount as in normal siblings). The aim is to see whether genetics or the environment have more of an influence on those traits. These studies have shown that identical twins have a more similar IQ, than non-identical twins. Furthermore, another study found that siblings (who share 50% of their DNA) raised in the same home, have more similar IQs than adopted children (who share none of their DNA) raised in the same home. Therefore, the researchers concluded that genetics are responsible for around 50% of the differences in intelligence amongst individuals.

To pinpoint the exact genes involved in intelligence, scientists have used Genome-Wide Association Studies (GWAS), where large groups of peoples’ DNA is sequenced to see if any differences in their DNA are associated with a particular trait. Unfortunately, these studies, so far, have been unable to locate individual genes that play a major role in intelligence; actually, it appears that multiple genes are involved, and it’s their combination that delivers the impact. In 2017, researchers scanned 78,308 individual genomes and found 22 specific genes linked to intelligence. However, they determined that these genes only account for 5% of the difference in intelligence amongst the individuals. More recently, in 2019, researchers looked at the genomes of 240,000 individuals, a considerably larger research group than the previous study; they found over 538 genes associated with intelligence. This confirms previous findings which suggest that many genes are involved, but individually, they have little impact on intelligence.

So, it appears that although no single gene is the cause of intelligence, many genes all working together do have an impact. However, it should be noted that some twin studies have shown that identical twins who share the same environment have more similar IQs than identical twins who were adopted separately, and therefore don’t share the same environment. This suggests that environmental influences are equally influential in intelligence as genes. Education, nutrition, parenting style, learning resources and access to green space are just a few of many other factors identified as an environmental influence on intelligence.

Overall, it appears that intelligence is significantly influenced by your genes, but environmental factors are equally a driving force in this trait. This makes studying the genetics of intelligence very difficult. Are you smart because your parents were smart? Or are you smart because your parents are smart, meaning they achieved higher paying jobs, meaning you were brought up in a nice area, meaning you received a higher level of education? Just because genes are identified as having a role in intelligence, it does not claim sole responsibility. One article concluded this nicely: ‘You may be born with specific genes… but making the most of those genes is still up to you.’

References

https://medlineplus.gov/genetics/understanding/traits/intelligence/

https://www.cambridgebrainsciences.com/more/articles/22-genes-have-been-linked-to-intelligence

https://www.southampton.ac.uk/news/2018/03/genes-intelligence.page

https://gajreport.com/meet-imafidon-uk-smartest-family/

https://medcraveonline.com/JNSK/factors-influencing-intelligence-quotient.html

 

Disclaimer

The information in this blog is for information and entertainment purposes only. I am not a medical professional, so I have never and will never give medical advice in this blog. You should always speak to a healthcare professional about your unique health needs. My opinions are entirely my own and do not reflect the organisations or people I work for. I only discuss published literature in this blog which are referenced with links.

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