Does Nature or Nurture Determine Your Personality?

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Blame it on your parents (nature). Blame it on your friends (nurture). But, in truth, you can probably blame your personality on both.

Is the development of human personalities the result of inherited genetic traits from parents or the layering of years of experiences through interaction with the surrounding environment (including friends) — nature versus nurture? Scientists have been arguing about this question for centuries. In fact, as far back as 400 BC, Hippocrates emphasized the commanding role of nature, when he identified four biological fluids – yellow bile, black bile, phlegm, and blood – as underlying the various classifications of all human behavior. That aside, thanks to 21st-century science and technology, the truer answer to personality may well be found in a seminal study published December 2017 in Nature Neuroscience.

In it, researchers from Harvard Medical School determined that after exposure to light, thousands of genes altered their expression within the visual cortex of the brain. The finding indicates a single sensory experience – or stimulus – essentially prompts a transcriptional cellular response that re-wires, or structurally remodels, brain function. “This in essence addresses the long-asked question about nature and nurture: Is it genes or environment? It’s both, and this is how they come together,” a co-senior author of the study is quoted as saying in an online Harvard University article.

Does This End the Nature vs. Nurture Debate?

Yet, the study does not fully answer the question about the development of personality, although the Harvard scientists offer definitive evidence that nature – inherited genes and other biological influences – and nurture – learning and exposure to influences of the surrounding environment – appear inextricably intertwined. Even the Harvard team suggests more investigation is needed. In the growing field of epigenetics, for example, experts are increasingly finding that experiences occurring early in a child’s development impact the child’s DNA and determine how his or her inherited genes express themselves.

To muddy the waters of personality theory even more, researchers literally took the question to the birds – zebra finches, that is – and reported in Biology Letters that personality traits can be transmitted “non-genetically” to offspring from one generation to the next through practiced behavior.

The Basics of Personalities

What exactly is personality? The basis of how we think – and how we are born (nature) – is defined as “temperament.” Temperament can be divided into recognizable childhood traits grouped within categories of energy, emotion, and what one might call fear (avoidance of the unfamiliar). But temperament is not static. It is malleable, continually changed by life experiences. This ongoing interplay between inherited temperament and environment is what builds and constantly rebuilds personality.

In a 2017 article in Psychological Review, author C.S. Dweck theorizes that personality develops from basic psychological needs, “need-fulfilling goals,” and the experiences, including beliefs, emotions, actions, accumulated in pursuing and achieving these goals. She defines basic psychological needs as the ability to predict the world, achieve competence to act within it, and gain the approval – acceptance – of others.

Just as no two individuals are alike, no two personalities are alike. However, scientists from Northwestern University found “higher densities” of certain personality types, which they categorized as average (which they say applies to a “typical” person), reserved, self-centered, or “role model.” Their report was published in a September 2018 issue of Nature Human Behaviour. Other investigators have subdivided personalities into five clusters: “neuroticism, conscientiousness, agreeableness, extraversion, openness to experiences.”

Into which personality category one might place himself or herself requires some considerable self-assessment. Being irritated at one’s boss, for example, is more an emotion or mood evoked by a single situation among many life experiences and not necessarily a personality quirk or flaw. But irritability in general with any and all people and events may have a much deeper biological basis.

Can We Change Our Personality?

If we are the product of multiple genetic and environmental forces over which we have little control, is it possible we can change any personality component that we simply do not like – or maybe a spouse or significant other does not like? Maybe, say experts. In a study appearing in the December 2019 issue of American Psychologist, researchers say the assumption that personality traits are “functionally unchanging…is both untrue and a limiting factor on using personality traits more widely in applied settings. [Personality] traits can serve…as relatively stable predictors of success and actionable targets for policy changes and interventions.”

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Other researchers agree. Writing in a 2020 issue of the Journal of Research in Personality, University of Arizona investigators report that altering aspects of one’s personality can be done, but the process is difficult, and most people cannot do it on their own. They suggest the importance of setting personality goals and then undergoing therapeutic coaching to achieve them.

But barring the hiring of a therapist for help in becoming a more extraverted, warmer, and agreeable individual, experts offer the following tips for self-improvement:

• Take your face out of your smartphone and become more engaged with the actual people in the world around you.
• Learn to be a truly “active” and empathetic listener – not simply one impatiently waiting or interrupting to tell your own story.
• Be well-read on important and significant issues in today’s world.
• Practice positive thinking. Argue for – and express — the good even in difficult situations.
• Remember: Those who are happiest tend to have the warmest personalities. So, find some enjoyable hobbies, stay in touch with friends, and be grateful for what you have.
• If you make promises, keep them; stop the excuses.
• Smile more.

In the words of German social psychologist and philosopher Erich Fromm, “Man's main task in life is to give birth to himself, to become what he potentially is. The most important product of his effort is his own personality."