One could make the fair argument that our personality is essentially what differentiates us from the over one hundred billion humans that have existed before us. That being said, how such personality traits actually originate is often the subject of heated debate. While recent advancements in genetics have offered great insight into how specific genes contribute to our personality, the path to fully understanding the matter is definitely not linear. Genes act as our building blocks, whilst our experiences determine what final structure those building blocks eventually take form.
The Heritability of Personality Traits
To measure the genetic influence on personality, researchers often turn to twin studies. By comparing identical twins (who share nearly all their genes) with fraternal twins (who share about half), scientists estimate heritability or the degree to which differences in a trait are due to genetics. Findings suggest that specific personality traits are affected differently by a person's genetic makeup. For example, studies show that social closeness is impacted by genes by around 15%, compared to that of imagination which is influenced by close to 74%. These findings show how our traits are still not "hardwired", even for traits more impacted by our DNA. Rather, it shows a strong level of interaction between our DNA and environment.
Epigenetics: The Environmental Influence on Genes
As we've come to see, our environment can significantly impact how our genes are actually expressed. This is entirely what epigenetics revolves around, a field that analyses how experiences can alter gene expression. Epigenetic studies show that early childhood events, including trauma, leave "epigenetic marks" that affect how these genes related to stress mitigation and emotional control are actually activated. This suggests that the layout of our genetic structure is flexible.
Genes and Mental Health
Recent research has interestingly shown that changes in specific genes are likely to result in developing mental health disorders. For instance, alterations in the COMT gene (which helps break down specific brain chemicals) are linked with higher chances of developing schizophrenia. Meanwhile, differences in the SLC6A4 gene (that manages the movement of serotonin, a brain chemical that impacts mood) are linked with higher depression rates. As research has progressed, there has been a lot more understanding of other genes that also influence these same conditions, such as BNDF and DISC1, which both are related to brain development. It is also noted that a lot of these genes play roles in neurotransmission (a mechanism by which brain cells are able to use chemicals to transfer messages to each other)
Future Directions in Personality Genetics
With the emergence of Genome-Wide Association Studies (GWAS), our knowledge of the link between genetics and personality continues to increase. Through analyzing DNA from large groups of people, scholars are able to identify genetic markers that are linked to personality traits. This helps provide greater insights into various genetic traits, from friendliness to agreeableness. While it definitely seems extremely promising, caution must be taken: oversimplifying complicated characteristics and overemphasizing genetic determinism (the belief that genes dominate someone's personality) are two common detrimental problems within the field of genetics.
That being said, the growing consensus is quite evident - our personalities are largely impacted by an interconnection between nature and nurture. Though we may be more likely to move toward certain tendencies, to what extent and how often we express these tendencies is still really influenced by the experiences we've encountered throughout our lives. As a result, in a world where everyone seemingly only cares about statistics and what is absolute, it is vital to also take a step back and remember that our personality isn't just dependent on our genetic code, but also on how we interact and communicate with the continuously changing world around us.
References:
DMSci, B. B., PhD. A discrepancy in heritability studies points to the environment’s impact. Psychology Today. August 3, 2020. https://www.psychologytoday.com/us/blog/the-superhuman-mind/202008/where-does-our-personality-come.
Gillette, H. Genetics and their role in personality disorder development. Healthline. https://www.healthline.com/health/mental-health/are-personality-disorders-genetic.
Admin-Science. Understanding the role of genetics in shaping personality traits. Genetics. https://scienceofbiogenetics.com/articles/the-impact-of-genetics-on-personality-unraveling-the-link-between-our-genes-and-who-we-are.
Uttam, R. Clinical Genetics and Mental health: How genetics can influence Mental illness. Medanta - the Medicity. https://www.medanta.org/patient-education-blog/clinical-genetics-and-mental-health-how-genetics-can-influence-mental-illness.
Kao, P.-Y.; Chen, M.-H.; Chang, W.-A.; Pan, M.-L.; Shu, W.-D.; Jong, Y.-J.; Huang, H.-D.; Wang, C.-Y.; Chu, H.-Y.; Pan, C.-T.; Liu, Y.-L.; Lin, Y.-S. A genome-wide association study (GWAS) of the personality constructs in CPAI-2 in Taiwanese Hakka populations. PLoS ONE 2023, 18 (2), e0281903. https://doi.org/10.1371/journal.pone.0281903.
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