Jealousy and Joy: The Genetics of Emotions

Why is it that I am left sobbing over the ending of ‘The Notebook’, when my best friend is sat stoically on the sofa next to me? Well, scientists have shown that the emotionality of an individual is variable and, at least partly, due to your genes. So, the fact that you’re crying over the advert of the two old people holding hands in the nursing home, may not just be because you’ve had three glasses of wine at dinner, but instead may be due to your genetics.

Using a questionnaire to establish emotional sensitivity, one study used twins to determine the influence of genes on emotion. The researchers compared the answers to these questionnaires in 1,000 identical twins (who share 100% of their DNA), compared to 1,800 non-identical twins (who only share 50% of their DNA, the same amount as in normal siblings). The researchers found that identical twins have greater similarity in emotional sensitivity scores compared to non-identical twins. The scientists in this study concluded that 47% of the difference in emotional sensitivity in individuals is due to genetics. This is in line with other, similar studies, who conclude that emotional sensitivity is 40-60% heritable. But how exactly are genes influencing emotions?

Emotions are not as simple as ‘how we feel about the world’ but are instead a complicated contribution of chemicals and brain circuitry, which process stimuli and trigger an emotional output. Genome-Wide Association Studies (GWAS) have analysed large groups of peoples’ DNA to determine whether differences in emotionality are associated with differences in their DNA sequence. These studies have identified hundreds of genes which influence the complex circuitries and mechanisms involved in emotional output.

A study by Todd et al focused on the influence of one of these many genes. These researchers found that a difference in sequence in the gene, ADRA2B, is associated with greater emotional sensitivity, or emotional ‘vividness’. They asked participants to look at a pixelated ‘neutral’ image, followed by a pixelated ‘emotional image’ and determine whether the ‘emotional’ image is clearer/ more vivid than the ‘neutral’ image. The authors found that all participants determined that the ‘emotional’ image was more clear/ vivid than the ‘neutral’ image, regardless of whether this was the case. Interestingly, when comparing the same image, participants with the variation in the ADRA2B gene consistently recorded the ‘emotional’ image as clearer than those without the gene variant. The authors suggested that this was because individuals with the gene variant experience emotions more intensely, thus record that they are seeing the ‘emotional’ images more vividly. When they scanned the brains of these participants, they found that those with the genetic variation had higher activity in brain areas responsible for emotion regulation.

However, emotionality is a very complex state to measure. An individual may feel strong emotions, and simply not express them. Others may be very good at expressing their emotions, perhaps to a higher level than the situation requires. Furthermore, the fact that 40-60% of emotionality is inherited, suggests that a significant influence over emotionality is our environment. Of course, it is incredibly difficult to tease apart the environmental factors from the biological factors; therefore, the contribution of the varying levels of expression of emotions, along with the difficulty to isolate genetics factors, makes the genetics of emotion a very difficult topic to study.

Overall, we see that a significant amount of our emotionality is due to our genetics, and researchers have investigated individual genes and their influence on emotional sensitivity. However, I can’t blame my blubbering over ‘The Notebook’, solely on my parents; childhood experience, time of year, tiredness, and an assortment of other environmental factors are also responsible for emotionality. Yet, with increased understanding into the genetics of emotionality, there may come an increased understanding of anxiety disorders and other mental health conditions. With enough understanding, there may even be a development of treatment. Therefore, the continuing investigation into the genetic factors influencing emotion remains vital.

 

References

https://pubmed.ncbi.nlm.nih.gov/21835681/

https://www.psychologytoday.com/us/blog/the-athletes-way/201505/how-do-your-genes-influence-levels-emotional-sensitivity

https://geneticliteracyproject.org/2018/11/16/emotions-and-memory-how-your-genes-impact-the-way-you-see-and-feel-the-world/

https://www.theweek.in/news/sci-tech/2020/06/03/are-you-highly-emotional-your-genes-may-be-to-blame.html

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3408019/

 

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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