As everyday people, we are generally aware that the inner workings within our bodies can affect how we get through life. If you have a headache while you are at work, you may become more irritable with your co-workers and feel disjointed overall. Or if you are fired from your job one day and out of work for weeks to months after that, you may become anxious, depressed, and socially withdrawn.
Perhaps you are usually extraverted, boisterous, charismatic. Or you are more introverted, introspective, shy, often quiet. Perhaps you grew up in a strict household with introverted parents; or a household filled with laughter and playful teasing; or you have certain ideological beliefs that guide your disposition and how you interact with other people; or you are part of a wealthy, aristocratic social status; or you live in an impoverished neighborhood with a high crime rate, and you have financial hardships.
All of the above examples are just a tiny fraction of the numerous factors that can shape human development and personality. But what exactly comprises personality? In the field of Psychology, personality is defined as the thoughts, feelings, and behaviors ascribed to individuals, including their uniqueness and universal attributes. (Cervone & Pervin, 2013).
Personality is further broken down into traits. The Big Fivepersonality model has been a well-established foundation to understanding personality differences. The five key traits – Openness, Conscientiousness, Extraversion, Agreeableness, and Neuroticism – are a guide to the degree in which individuals possess any or all of these traits. For instance, highly caring people display conscientiousness; creative people fit with openness; engaging, highly sociable people fall under extraversion; trusting, well-adaptable people align with agreeableness; and people who are frequently depressed and anxious may be experiencing neuroticism (Cherry, 2020).
Yet what is the thread that weaves through The Big Five personality model? Is it biologically based? Is it environmentally based? Is it both?
It turns out that both biology and environment contribute to personality development, traits that may remain consistent throughout a lifespan, and perceptions about other people. Biology and environment are also referred to as Nature and Nurture, respectively. Now 140 years ago, these terms were first coined by Sir Frances Galton and have since grown into the foundational underpinnings of scientific inquiry and the ever-growing advances in psychology (Cervone & Pervin, 2013).
This paper examines the nature versus nurture roles in gene-environment interaction, how twin studies substantiate gene inheritability, how culture plays a role in personality traits, why temperament and stability measures help us more accurately understand trait consistency, and how the Big Five personality model and biological factors thread into all of these topics.
Beginning with gene-environment interaction, let’s understand how the two correlate. First, although the very term gene is rooted in biology — and that science has clearly established that people can have genetic pre-dispositions to physical features, brain function, health issues, and behavioral patterns — that does not mean that biological (nature) and environmental (nurture) influences on personality are in completely independent categories. Rather, there is plenty of data to show that nature and nurture influence each other in many ways (Dick, 2013).
For instance, one study showed that people pre-disposed to needing excitement and sensational experiences are more likely to frequent busy social settings, such as bars, concerts, etc. On the other hand, a person who is not genetically pre-disposed to seeking out thrills and excitement could become more prone to seeking that out after being exposed to highly social environments. In other words, the degree to which genetics and/or environment affect personality traits is not quite clear-cut (Dick 2013).
Yet it is still necessary to understand how nature and nurture affect each other. In fact, gene-environment interaction can be split into three categories: active, passive, or evocative. Active interaction applies to people who often seek out social situations and prefer not to be alone. Passive interaction is produced when a person is genetically predisposed to abusive or isolative behaviors, and the environment matches that. Lastly, evocative interaction occurs when a person is predisposed to emotional outbursts (for example, children with their caregivers), and the people on the receiving end, in-turn, react with their own emotional outbursts (Dick, 2013).
Now that we have a basic understanding of gene-environment interaction, how do we go about further understanding their dynamic? The answer, of course — case studies. Specifically, twin studies. And why twin studies? Because they have provided a wealth of information about gene hereditability. From what is now considered a classic study – that is, comparing monozygotic to dizygotic twins — we know that that genetics have a component in all areas of human development (Turkenheimer et al, 2010).
Let’s examine some information that supports the positive claims about twin studies: Between 1979 and 1999, a study on 350 sets of twins showed that whether a pair of identical twins are raised in the same home or in different homes, the twins will still share many of the same personality traits, averaging around 50% in similarities, while not negating environmental factors. Conversely, fraternal twins share 20% similarities in traits (Cherry, 2020).
What this ultimately means is that genes certainly have a role in personality traits. However, because environment remains a factor as well, twin studies have had to evolve to incorporate as many pertinent factors as possible. For example, twin studies were criticized in the past for either being too limited in their scope, or that some studies were biased in how they were formulated. This was primarily due to how gene influence had been first studied. That is, a gene can have an additive mechanism (two genes specifically come together to produce a single trait) or an epistatic mechanism (various genes merge to create a single trait). Twin studies have tended to focus more on additive mechanisms to confirm gene inheritability (Winerman, 2004).
In the present day, twin studies are now even more comprehensive, including incorporating longitudinal studies and more precisely measuring environmental factors, such as family influence and other personal experiences that may affect a personality trait. Further, with the rise of molecular genetics, studies are not only investigating gene hereditability, but also the exact effects that a singular gene produces (Winerman, 2004).
So far, we see that genes play an important role in personality traits, and that environment is influential as well. Moreover, the term environment has many of its own variables: family life, work, romantic relationships, poor neighborhoods, wealthy neighborhoods, stress triggers, exciting experiences versus mundane routines, belief systems, and generally dealing with other varying personality types. That said, how about culture? How does that fit in with environmental influences?
First, let’s define culture: Culture, simply put, comprises all the components that establish a society: traditions, social hierarchies, arts and music, language, and belief systems. However, as the term is often used to describe a specific country, or a particular tradition, or even now a corporate set of values in the business world, culture is actually quite a bit broader than that (Lumen, 2020). In just the U.S. alone, we have separate cultures by regions, by political affiliations, by sexual orientation and lifestyle, by sports fans and their favorite teams, and by a plethora of other collectivist labels.
Then, how exactly does culture affect personality traits? Using the Big Five personality model with studies conducted on societies throughout the world, we have learned that the more complex the society, the more that personality traits vary, and the more they can vary from other cultures (Arakelian, 2019).
This has led to separating cultural studies into three main approaches: indigenous, cultural-comparative, and a combined approach. The indigenous approach has helped shift cultural studies from being more Western based – which was an issue in initial studies – to understanding personality in more primitive societies. The cultural-comparative approach has helped validate the Big Five across cultures. And the combined approach has helped determine which aspects of personality are universal, and which ones are different, particularly between indigenous and Western cultures (Lumen, 2020).
Yet we cannot fully discuss cultural, environmental, and biological factors about personality without also including temperament. Interestingly, there has been some debate regarding what degree that temperament varies from personality. For example, a study conducted on a group of undergraduate studies showed a strong relationship between personality and temperament. Namely, the Big Five personality model and the four dimensions of temperament — effortful attention, extraversion, negative affectivity and orienting sensitivity – are so cross-connected, that personality and temperament can be viewed as the proverbial two sides of the same coin (Rettew & McKee, 2005).
However, just because personality and temperament have their similarities, it does not mean that temperament does not have its own characteristics and varying perspectives: One angle is that while temperament is tied to personality throughout a lifespan, it still operates as a separate factor to how personality traits remain or morph over time. Another angle explains temperament as base set of reactionary patterns that are the precursor to personality development. And still yet another angle, based on a study conducted on children in Russia, shows a clear link between the Big Five model and temperament as the initial driver of personality development (Rettew & McKee, 2005).
Nevertheless, all angles aggregate up to another aspect of temperament: stability. While there are many methods of studying stability, the two primary methods are differential and absolute. Differential stability provides a biologically driven, ranked approach to temperament consistency across an individual’s lifespan. Absolute stability involves trait changes or consistency in a group of individuals within an environment or set of environments. (Neppl et al, 2011).
Researching differential stability has been especially useful in identifying the ways that genes influence temperament and, in turn, personality. If a child, say, is genetically pre-disposed to aggressive behaviors or violent tendencies, then the child’s temperament may show signs of those tendencies. However, because environment is yet again a factor in child development and maturation, environmental influences can have a dramatic effect on whether a child grows into an adult who acts on violent impulses, or who has matured into a more balanced individual from caregivers who have openness and conscientiousness traits (Neppl et al, 2011).
While this paper has delved a bit under the surface to explore nature versus nurture, the scientific inquiry on this is still evolving. And as interdisciplinary studies become more common in linking personality traits to the combination of biological and environmental causes, we can continue to bridge nature and nurture as co-contributors to the Big Five.
References
Cherry, K. (2020). Are Personality Traits Caused by Genes or Environment?. https://www.verywellmind.com/are-personality-traits-caused-by-genes-or-environment-4120707
Cervone, D., & Pervin, L. A. (2013). Personality: Theory and research (12th ed.). Hoboken, NJ: John Wiley & Sons, Inc.
Dick, D. (2013). Gene-Environment Interaction in Psychological Traits and Disorders. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3647367/
Johnson, W., Turkheimer, E., Gothesman, I., Bouchard, T. (2010). Beyond Heritability: Twin Studies in Behavioral Research. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2899491
Arakelian, E. (2019). Cognitive Scientist Shows How Culture Shapes Personality Traits. https://news.ucmerced.edu/news/2019/cognitive-scientist-shows-how-culture-shapes-personality-traits
Lumen. (2020). Cultural Understandings of Personality. https://courses.lumenlearning.com/suny-intropsychmaster/chapter/cultural-understandings-of-personality/
Winerman, L. (2004). A second look at twin studies. https://www.apa.org/monitor/apr04/second
Neppl, T., Donnellan, B., Scaramella, L., Widamin, K., Spilman, S. (2010). Differential stability of temperament and personality from toddlerhood to middle childhood. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2902199/
Rettew, D., McKee, L. (2005). Temperament and Its Role in Developmental Psychopathology. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3319036/