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Sensitivity is in our genes (but not only!)

1st August 2020 - By Elham Assary

About the authors

Elham Assary is a postdoctoral researcher at Queen Mary University of London. Her research aims to understand how the interaction between genes and the environment influence the development of psychopathology or resilience to it. Her current research uses a range of behavioural and molecular genetic methods to investigate which genetic factors relate to variations in sensitivity to positive and negative environments and how they affect the outcomes of such environmental exposures.

Summary

Our study investigated the heritability of sensitivity. Results showed that 47 percent of the differences in sensitivity between individuals are genetically determined, whereas the remaining 53 percent are accounted for by environmental factors. In addition, we also found that part of this heritability is shared with the personality traits neuroticism and extraversion.

Background information

Some people are more sensitive than others, and most theories on sensitivity suggest that differences in sensitivity have e genetic basis. Previous studies have investigated whether specific genes make some people more sensitive than others (1). However, no study so far has provided an estimate for how much genetic factors contribute to sensitivity.

Study Aims

In our current study (2), we compared the similarity in sensitivity of identical with non-identical twin pairs to determine the heritability of sensitivity.

Heritability describes what proportion of the differences between people in relation to a particular trait can be attributed to genetic factors alone.

Given that identical twin pairs share the same genes, non-identical twin pairs only share half of their genes, and that both types of twins share the same environment, greater similarity of identical twins  compared to non-identical twins indicates the existence of a genetic basis for the examined trait.

How the study was conducted

In our study, we collected data from more than 2,800 identical and non-identical twins from the UK who have taken part in the Twins Early Development Study. The participants were about 17 years old when the data were collected. Around 1,000 of the participants were identical twins and the remaining 1,800 non-identical twins, roughly half of whom were same sex.

Participants were asked to fill out a questionnaire (3) that measured their sensitivity levels. The questionnaire asked them how much they usually get affected by various psychological and sensory experiences. For example, they were asked how much they notice when small things around them have changed, whether loud noises make them feel uncomfortable, and whether they dislike watching violent TV programmes.

Additionally, in order to establish how genetic influences on sensitivity relate to other common personality traits, we also collected data on the Big Five personality traits, namely openness, conscientiousness, agreeableness, extraversion and neuroticism.

Key findings

We found that 47% of the differences in peoples’ sensitivity are indeed explained by genetic factors. But the remaining 53% of a person’s level of sensitivity is shaped by life experiences. In other words, genetics accounts for just under half of the reason an individual may be a more sensitive person.

Importantly, our research examined the genetic basis of sensitivity in more detail. We wondered whether sensitivity was made up of one genetic component or multiple ones. We found that sensitivity is composed of multiple genetic components that together make up a person’s specific type of sensitivity.

Besides a general genetic component for sensitivity, we also found a component associated with sensitivity to negative experiences and a component that reflects sensitivity to more positive experiences. This means that genetics influence why some people may be more sensitive than others in general, and also whether they  may be more sensitive to either the positive or negative things that happen to them.

In relation to personality traits, we found that there is a shared genetic component between sensitivity, neuroticism, and extraversion, but not with any of the other personality traits.

General conclusion

Uncovering how genes shape sensitivity is important in our understanding of why some individuals fare worse in response to traumas and stressors – and why some benefit more from interventions aimed at promoting resilience and health.

Although our study did not examine what the specific genes are that make some people more sensitive than others, it did show that sensitivity is a heritable trait with a substantial genetic basis.

More importantly, these finding provide further evidence supporting the fact that sensitivity is a common human trait. We know from previous research that around a third of people are at the higher end of the sensitivity spectrum, meaning that they are generally more strongly affected by their experiences. This can have both advantages and disadvantages. Because we now know that this sensitivity is as much due to biology as environment, it is important for people to accept their sensitivity as an important part of who they are and consider it as a strength not just as a weakness

References

  1. Belsky, J., Jonassaint, C., Pluess, M., Stanton, M., Brummett, B., & Williams, R. (2009).Vulnerability genes or plasticity genes?Molecular Psychiatry, 14, 746–754.
  2. Assary, E., Zavos, H. M. S., Krapohl, E., Keers, R., & Pluess, M. (2020). Genetic architecture of Environmental Sensitivity reflects multiple heritable components: a twin study with adolescents. Molecular Psychiatry. https://doi.org/10.1038/s41380-020-0783-8
  3. Pluess, M., Assary, E., Lionetti, F., Lester, K. J., Krapohl, E., Aron, E. N., & Aron, A. (2018). Environmental sensitivity in children: Development of the Highly Sensitive Child Scale and identification of sensitivity groups. Developmental Psychology, 54(1), 51–70. https://doi.org/10.1037/dev0000406