"It's in my DNA": How Your Genes May Actually Affect Personality
"It's in my DNA": How Your Genes May Actually Affect Personality
Karena Peterson, 6/24/24
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A common saying in English is that certain traits or behaviors are “in our DNA” or “a part of who we are.” These phrases are often used ironically, but what if this can be taken in a literal sense, at least partially? Could certain traits truly be influenced by the genes on our DNA? Studies, such as research on genetically related twins and families, provide insight on how our genetic makeup influences temperament. It has been suggested by multiple current studies that personality and specific traits can be influenced to some degree by multiple genes, however it is debated how significant that degree is, how exactly genes play a role, and how environmental factors also come into play.
Popular studies on this matter often discuss the heritability of personality, usually with studies on genetically related families, more specifically, twins. These studies are often very insightful. Identical twins (twins who share 100% of their genes) are typically more similar to each other in personality than non-identical twins (share 50% of their genes) or other genetically related siblings, which could prove that personality is partially inheritable, thus controlled partially by genes. This would explain why being genetically similar often results in more psychological similarities. Heritability estimates, or estimates of, “statistical [concepts] that [describe] how much of the variation in a given trait can be attributed to genetic variation” (MedlinePlus, What is heritability?) vary for each trait. However, according to a meta-analysis, the heritability for the Big Five traits (openness, conscientiousness, extraversion, agreeableness and neuroticism- a common theory that describes the basic dimensions of personalities) ranges from 31- 41%. This number suggests that 31-41% of variation in the Big Five is due to genetic variation. Note, however, that this will vary when looking at specific studies. Looking at the similarities in personality within identical twins suggest genetics’ partial role in personality and the variance of personality traits.
There are also specific gene variations that have been linked to certain traits. For example, “DRD2 and DRD4 genes have been linked to a desire to seek out new experiences” (MedlinePlus, Is temperament determined by genetics?). Furthermore, according to recent Genome Wide Association Studies (GWAS, studies that scan the genomes of a large group of people to find variations within genes associated with specific traits, diseases, etc.), over 700 genes strongly influence temperament. This shows that genetics clearly play a role in our personalities.
Despite this, it has been theorized that genes do not play as significant of a role to the determination of personality as has been previously concluded. Many studies, such as the ones previously discussed, have looked at the heritability of personality over family relations and genetically identical twins. These studies often are often interpreted that thanks to the inherit, albeit unclear heritability patterns of behaviors, biological children to parents likely inherit genes that affect personality; suggesting there are personality-altering genes to inherit. However, some have argued that just because children are more likely to have traits that their parents possess, it does not mean they are directly inherited via genetics. Instead, it has been proposed that similarity in personalities and behaviors do not come from shared personality-altering genes, but from other shared trait’s genes code for. This is based on the idea that individuals with certain physical traits will often adapt personalities, behaviors and habits that are a result of physical traits. An example of this could be a trend between taller heights and interpersonal dominance. It has been found in some studies that taller individuals are more likely to exhibit dominant and assertive behaviors within social interactions or relationships. If both a parent and a child are considered taller and exhibit the personality trait of interpersonal dominance, it would not necessarily be from inheritance of specific genes coding for dominance, but possibly from the shared taller heights of both the parent and the offspring, and therefore the development of a more dominant and assertive personality as a result of their physical stature. Essentially, this argues that major similar psychological traits are not from personality-affecting genes being inherited, but from inherited physical traits which the shared personality is then derived from. This argument has been used by some to discredit the conclusion that a significant amount of personality is controlled by genes, drawn from identical twin studies, as identical twins shared physical traits, which according to this idea, could also explain the similarity in personality. Furthermore, while it is typically acknowledged, by many scientists, that it is a reasonable conclusion that genetics play somewhat of a role, it has been debated if it can really boil down to just one or a few determining genes per trait. Large studies have shown that differences in psychological traits are possibly due to thousands of variations along DNA strands- each one making minute alterations. This proposes the question: can one or even a handful of genes be correlated to specific traits, if it takes thousands to potentially affect behaviors? However, many scientists continuously label and acknowledge personalities potentially influenced by genes as polygenic- recognizing that these traits are not controlled by a single gene, same as other polygenic traits.
Finally, even after recognizing genetics' role in psychological traits, the significance of an individual’s environment is frequently discussed. This leads to a common debate of which one plays a more significant role, referred to as Nature (genetics) vs. Nurture (environment). While it is undeniable that environmental factors-ranging from lighting to high-stress homes- change behavior, this does not discredit genetics' own affect on personality. According to an article published on National Center for Biotechnology Information, The Heritability of Personality is not Always 50%: Gene-Environment Interactions and Correlations between Personality and Parenting, personality is not, “solely a product of environmental forces acting ‘from the outside’; personality is also the result of a genetic blueprint leading the person to actively seek out and interpret external environments in unique ways.” In other words, genetics and environment work together to affect personality. Furthermore, according to a MedlinePlus article, Is temperament determined by genetics, certain genes may be activated, or turned on in specific environments- alluding to how intertwined the environment and genes are when talking about which one is more significant. Overall, controversy with the question, “Do genes affect personalities?” don’t usually doubt that genes play somewhat of a role, but more so question how genetics affect personality- directly, or as a result of coded physical traits-, the significance of each gene, and how the environment comes into play.
So, when asking the question, “Do genes affect personality?”, a simple answer based on current research would be yes. While some factors of how exactly genes play a role are questioned- their significance, nature vs. nurture, etc.- more and more studies are coming out with evidence that DNA influences personality, however it is still hard to confidently pin which gene variants affect traits. In the end, both the environment and genetics play a role to personality, so yes, it may be “In your DNA.”
References:
Is temperament determined by genetics?: MedlinePlus Genetics
The genetics of human personality - PMC (nih.gov)
Why Personality Is Not Genetically Hardwired | Psychology Today
Human Height Is Positively Related to Interpersonal Dominance in Dyadic Interactions - PMC (nih.gov)
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