Two children can grow up in the same household, with the same parents, similar opportunities and shared childhood experiences, yet develop completely different personalities. One might be sociable, spontaneous, and eager to explore the world, while the other is more reserved, cautious, and comfortable with routine. Even within the same family, differences in temperament can become apparent from an early age. This raises the question: how much of our personality is already determined when we are born, and how much develops along the way?
Philosophers and scientists have debated the relative importance of nature versus nurture in shaping human behaviour for millennia, from Galen’s biological temperaments in ancient Greece to John Locke’s 17th century concept of the tabula rasa. On one side are genetic predispositions inherited from our parents; on the other are the influences of upbringing, education, culture, relationships, and personal experiences. However, these two explanations are not mutually exclusive. Increasingly, research suggests that personality develops through a continuous interaction between the two.
Genetics undoubtedly plays a role in shaping individual differences. Certain tendencies, such as sociability, emotional sensitivity, or curiosity may have a biological component. Personality psychologists often describe these differences through the “Big Five” model, which groups personality into five broad dimensions: openness to experience, conscientiousness, extraversion, agreeableness, and neuroticism. Rather than placing people into rigid categories, the model recognises that everyone falls somewhere along each of these five dimensions.
A study published in the scientific journal Nature in September 2026, involving scientists from the University of Tartu in Estonia, analyzed genetic data from up to 1.14 million people to investigate genetic associations with the Big Five personality traits. By examining genetic information alongside personality assessments, the researchers sought to better understand why people differ in the way they think, feel, and behave. Their findings provide further evidence that genes are involved in personality differences, while also illustrating the complexity of translating genetic information into an understanding of individual behaviour.
Although personality traits show baseline stability, they are not entirely fixed.
Nevertheless, genes are only part of the picture. Growing up in a particular family, attending school, forming friendships, and experiencing different cultures all contribute to personality development. Even seemingly ordinary experiences can influence how people perceive the world and interact with others. A child encouraged to explore unfamiliar situations might become more confident in new environments, while someone who experiences repeated criticism may become more hesitant to express their opinions. Importantly, the same experience can affect different individuals in different ways.
This also helps explain why siblings can turn out so differently. Sharing a home does not mean sharing an identical childhood. Parents may unconsciously respond differently to each child’s temperament, siblings have different friendships and interests, and experiences that seem insignificant to one person can have a lasting effect on another. Furthermore, children do not simply adapt to their surroundings; their own characteristics influence the environments they seek out. A naturally curious person may pursue unfamiliar experiences, which in turn encourage further curiosity. In this way, nature and nurture continuously influence one another.
Although personality traits show baseline stability, they are not entirely fixed. An introverted person might become comfortable speaking in public through career experience or life shifts like entering the workforce, illustrating the key distinction between underlying trait temperament and adaptable behavior. Long-term studies, including the Canadian Longitudinal Study on Aging, demonstrate how major life environments continuously shape our psychological resilience and behavioral habits over decades, proving that personal development remains active across the entire lifespan.
Ultimately, the question of whether people are born the way they are or become that way through experience has no simple answer. Our genes may influence the foundations of our personality, but they do not dictate who we become. The environments we grow up in, the people we meet, and the experiences we accumulate all contribute to shaping us throughout our lives. Perhaps we cannot choose the starting point, but that does not mean the rest of the story has already been written.
This article was written by Emma Nahkor as part of the Local Journalism Initiative.
