Author: Alina Yang
Editors: Kevy Chen, Chiara Chen
Artist: Tracy Xu
Consider the twins you know–how similar are their personalities and behaviors? Now, extend your reflection to some non-twin siblings, perhaps within your own family. To what degree are their personalities similar or different? Most of us would say that, despite being raised in identical households, twins exhibit a greater degree of similarity compared to non-twin siblings. Studies in the Student Psychology Journal have shown that the correlation in personality traits between identical twins was observed to be twice as pronounced as observed among non-twin siblings. This prompts the question, what comprises the relationship between nature and nurture in shaping the personality of an individual?
To answer this complex question, we must delve into the realm of genetics. Nativism, in the field of psychology, is the contemporary belief that skills and abilities are hard-wired, innate traits. This concept is most associated with the work of Jerry Fodor (Modularity of Mind Hypothesis) and Noam Chomsky (Theory of Universal Grammar), whose studies both contribute to linguistic psychology. Both of these studies establish a common ground that the human brain is composed of innate neural structures that serve developmental functions, such as an evolutionary disposition to learn language. These fundamentals of nativism may also be applied to personality development, where studies have shown that inherited traits act as a blueprint, influencing the personality of an individual.
As we unfold the intricacies of DNA, studies have shown that our genome, a complex set of inherited instructions that directs how we will grow, also predisposes us to certain personality traits. In 1949, D.W. Fiske developed the “Five-Factor Model,” which displays the “Big 5” personality traits – agreeableness, extraversion, conscientiousness, neuroticism, and openness. Each of these five personality traits is a middle ground between the two extremes of each personality. Studies on twins reveal substantial heritability of traits such as extraversion and neuroticism. Genetics seems to set the stage for baseline tendencies in the Big 5 personalities, offering a glimpse into the inherent aspects of personality.
However, later research has proved that environmental, or nurture, factors can change one’s predominant personality over time. In childhood, personality traits tend to exhibit a degree of stability, but in one’s adolescence and young adulthood, personality traits frequently undergo significant and sometimes drastic changes. Theories of empiricism created by John Locke, George Berkeley, and David Hume support the idea that learning and development come from observation and experience. This is based on a premise rooted in linguistic psychology, which asserts that children learn vocabulary through auditory exposure, supplementing inherent linguistic predispositions as hypothesized by Noam Chomsky. Empiricism, however, asserts that the mind is a blank slate at birth; external or environmental factors seem to be our sculptor, shaping who we become later in life and giving personality a flexible nature.
A key component of developmental psychology primarily focuses on how the “nurture” aspect of personality, consisting of sociocultural experiences and interactions, significantly influences the expression of the “Big 5 Personality Traits.” In the instance of conscientiousness, one’s ability to regulate impulses, ranging from perfectionism and workaholism to irresponsibility and distractibility. can be shaped by the level of support and discipline one receives in their upbringing. Similarly, social interactions and experiences can contribute to the development of extroversion or introversion. Evidently, there is an intricate interplay between nurture and nature in the theory of the Big Five personality traits.
In a study of the heritability of the Big Five personality traits in the Department of Psychiatry at the University of British Columbia, the etiology of each trait was measured in over two hundred pairs of fraternal and identical twins:
Neuroticism: 41% genetic influence, 59% environmental influence
Extraversion: 53% genetic influence, 47% environmental influence
Openness: 61% genetic influence, 39% environmental influence
Agreeableness: 41% genetic influence, 59% environmental influence
Conscientiousness: 44% genetic influence, 56% environmental influence
As psychological inquiry delves deeper into this web of nature versus nurture, it becomes apparent that the development of psychology is not dictated solely by either nature or nurture. Rather, one’s personality is an emergence of dynamic interaction. Based on the theoretical framework of the Big Five Personality traits, some genetic predispositions could be influenced by external factors, while over remain unchanged. Throughout one’s lifetime, these complex combinations lead to unique personalities in every individual.
Citations :
Publisher, A. removed at request of original. (2015). 11.3 Is Personality More Nature or More
Nurture? Behavioral and Molecular Genetics. Open.lib.umn.edu.
Samet, J., & Zaitchik, D. (2012). Innateness and Contemporary Theories of Cognition (Stanford
Encyclopedia of Philosophy). Stanford.edu. https://plato.stanford.edu/entries/innateness-
Exeter, U. of. (n.d.). Personality is the result of nurture, not nature, suggests new study on birds.
Lim, A. G. Y. (2023). Big Five Personality Traits: The 5-Factor Model Of Personality. Simply
Jang, K. L., Livesley, W. J., & Vemon, P. A. (1996). Heritability of the Big Five Personality
Dimensions and Their Facets: A Twin Study. Journal of Personality, 64(3), 577–592.
Duignan, B. (2016). Empiricism. In Encyclopædia Britannica.
Bijani, H., & Nahvi, A. (2012). Modularity of Mind and Second Language Acquisition.
Theory and Practice in Language Studies, 2(8). https://doi.org/10.4304/tpls.2.8.1656-1661
Brennan, P., & Gogan, D. (2013). A Comparison of Twin and Non-Twin Siblings’ Use of
Relational Maintenance Behaviours and Associate Measures of Sibling Liking. Student
Psychology Journal, 1(14).