Last updated on October 2nd, 2026 at 09:53 pm
Raised in the same Akron house by the same parents, two brothers grew up opposites: one loud and adventurous, the other quiet and careful.
Personality is your characteristic pattern of thinking, feeling, and behaving- the qualities that make you recognizably you across situations and years.
The Akron brothers shared a home, parents, and many genes, yet their personalities diverged, which is exactly the puzzle personality science tries to solve.
Research shows that personality develops through a mix of inherited temperament, life experiences, relationships, and culture, and that it keeps changing well into adulthood.
This pillar explains what personality is, the major theories behind it, how it develops from infancy through old age, whether it can change, and practical ways to grow.
It also links to deeper posts on traits, identity, and specific personality patterns.
Table of Contents
What Is Personality?
Psychologists define personality as the relatively stable patterns of thoughts, feelings, and behaviors that distinguish one person from another.
“Relatively stable” matters: a cheerful person can have a bad day, but across many situations, their typical patterns show through.
Personality influences how you react to stress, how you relate to others, what work suits you, and even your health.
Personality is related to, but different from, character and identity.
| Term | Meaning | Example |
|---|---|---|
| Personality | Typical patterns of thinking, feeling, and behaving | Outgoing, anxious, curious |
| Temperament | Inborn emotional and behavioral tendencies seen early in life | A baby who is easily soothed |
| Character | Moral qualities and values shown in conduct | Honesty, fairness, courage |
| Identity | Your sense of who you are and where you belong | “I’m a teacher, a mother, and a Nigerian American” |
Identity is explored fully in what identity really means.
Major Theories of Personality
Psychologists have explained personality in several ways, and each theory captures part of the picture.
| Theory | Key Thinkers | Core Idea |
|---|---|---|
| Trait theory | Gordon Allport, Raymond Cattell, Robert McCrae and Paul Costa | Personality consists of measurable traits, such as the Big Five |
| Psychodynamic theory | Sigmund Freud, Carl Jung | Unconscious drives and early experiences influence behavior |
| Humanistic theory | Carl Rogers, Abraham Maslow | People naturally strive toward growth and self-actualization |
| Social-cognitive theory | Albert Bandura, Walter Mischel | Personality arises from the interaction of thoughts, behavior, and environment |
| Biological theory | Hans Eysenck, Jerome Kagan | Genes, brain chemistry, and temperament underlie personality |
Trait Theory
Trait theory is the most widely used approach in research today. It describes personality as a set of dimensions on which everyone varies, rather than fixed types.
Psychodynamic Theory
Freud proposed that personality emerges from conflict between unconscious desires and social rules. His ideas influenced therapy and culture, but many specific claims have little scientific support.
Humanistic Theory
Rogers and Maslow emphasized free will, personal growth, and the need to become one’s best self, ideas that still inspire coaching and counseling.
Social-Cognitive Theory
Bandura argued that behavior, thoughts, and environment influence one another in a loop he called reciprocal determinism, which explains why the same person can act differently in different settings.
Biological Theory
Research on temperament and genetics shows that some personality tendencies appear in infancy and are partly inherited.
The Big Five Personality Traits
The most researched model is the Big Five, also called OCEAN: openness to experience, conscientiousness, extraversion, agreeableness, and neuroticism.
Each trait runs along a spectrum, so people are not simply extraverts or introverts but fall somewhere between.
The Big Five appear across many cultures and predict outcomes such as job performance, relationships, and health.
Each trait is explained in depth in the five core personality traits, and introversion is explored in the introvert personality.
How Personality Develops
Temperament: The Starting Point
Personality begins with temperament, the emotional and behavioral style babies show from birth.
In their New York Longitudinal Study, psychiatrists Alexander Thomas and Stella Chess classified about 40 percent of infants as “easy,” 10 percent as “difficult,” and 15 percent as “slow to warm up,” with the rest showing mixed patterns.
Temperament does not fix adult personality, but it influences how children respond to the world and how the world responds to them.
Genes
Genes play a substantial role. A massive 2015 review led by Tinca Polderman, covering twin studies of more than 14 million twin pairs, found that across all human traits studied, about half of the variation was linked to genetic differences.
For personality specifically, twin studies commonly estimate heritability at around 40 to 50 percent.
Heritability describes differences between people in a population, not how much of any one person’s personality is “caused” by genes.
Environment
The other half comes from environment, and surprisingly, the shared family environment explains less than many people expect.
Siblings like the Akron brothers differ partly because each has unique experiences, friends, teachers, and roles in the family.
The interplay of genes and experience is explored in nature, nurture, and identity.
Parenting and Attachment
Warm, responsive parenting tends to support emotional security, while harsh or neglectful parenting can increase anxiety and difficulty trusting others.
Early emotional skills are covered in how children develop emotionally.
Culture
Culture influences which traits are valued and expressed. Some cultures prize assertiveness and independence, while others value modesty and harmony, encouraging different patterns of behavior.
Life Experiences and Roles
Major roles, such as starting a career, marrying, or becoming a parent, tend to encourage more responsible, stable behavior.
Psychologists call this the social investment principle: committing to adult roles nudges personality toward maturity.
Personality Across the Lifespan
Personality is not set in stone after childhood. A meta-analysis by Brent Roberts, Kate Walton, and Wolfgang Viechtbauer, drawing on 92 longitudinal samples, found that personality traits continue to change throughout life.
People tend to become more conscientious, more agreeable, and more emotionally stable as they age, with the largest changes between about 20 and 40. Researchers call this pattern the maturity principle.
Adolescence brings its own shifts, as teenagers explore identities and test boundaries, a process described in how identity forms.
In later life, openness and social energy may decline slightly, while warmth and emotional stability tend to remain high.
Can You Change Your Personality?
Yes, within limits. A 2017 review led by Brent Roberts examined 207 studies and found that interventions, mostly therapy, were linked to marked changes in personality traits over an average of 24 weeks.
Emotional stability changed most, followed by extraversion, and the changes persisted in follow-up studies.
Other research suggests that people who want to change a trait, and practice new behaviors consistently can shift it gradually.
Change does not mean becoming a different person. A naturally quiet person can become more comfortable speaking up without turning into the life of every party.
Personality Types vs Personality Traits
Popular tests such as the Myers-Briggs Type Indicator sort people into types, such as “introvert” or “extravert,” and are widely used in workplaces.
Researchers prefer trait models because most people fall in the middle of each dimension rather than at the extremes.
Studies have also found that many people receive a different Myers-Briggs type when they retake the test only weeks later, which limits its reliability.
Type tests can still spark useful reflection, but trait measures such as the Big Five are better supported by evidence.
Personality and Life Outcomes
Personality traits predict many important outcomes. Conscientiousness is linked to better health, longer life, and stronger job performance, while high neuroticism is linked to greater risk of anxiety and depression.
Agreeableness supports cooperative relationships, and openness is associated with creativity and learning.
Some traits can become problems when extreme, such as the harsh, critical style described in the abrasive personality, or the patterns covered in negative personality traits.
Personality and Identity
Personality describes how you tend to act; identity describes who you believe you are.
The two influence each other: a curious person may build an identity as a learner, and an identity as a caregiver may strengthen warmth and patience.
A stable sense of self helps people use their personality wisely rather than feeling ruled by it.
In the online world, people also present curated versions of themselves, a topic explored in your digital identity.
How to Develop Your Personality
Know Your Starting Point
Take a reputable Big Five assessment and ask trusted people for honest feedback, building honest self-awareness.
Choose One Trait to Grow
Pick a specific change, such as becoming more organized or more comfortable with strangers.
Act Before You Feel Ready
Behave the way someone with that trait would, in small steps; repeated behavior gradually becomes habit.
Build Supportive Habits
Turn the change into routines, using approaches from how good habits stick.
Seek New Experiences
Travel, new roles, and new friendships stretch personality, especially openness.
Get Support When Needed
Therapy can reduce anxiety and build emotional stability, the trait most responsive to intervention.
Respect Your Nature
Grow without forcing yourself into a personality that does not fit. A quiet, thoughtful person does not need to become loud to thrive.
Personality and Identity Topics at a Glance
| Topic | What It Covers | Read More |
|---|---|---|
| Big Five traits | The five core dimensions of personality | the Big Five explained |
| Negative traits | Unhelpful patterns and how to change them | unhelpful personality traits |
| Abrasive personality | Harsh, critical interpersonal styles | the abrasive personality explained |
| Introversion | Traits, strengths, and challenges of introverts | the introvert personality |
| Identity | Who you are and how identity forms | what identity means |
| Digital identity | How you present yourself online | identity in the digital age |
| Stoic personality | Calm, reserved temperament | the stoic personality type |
Conclusion
The Akron brothers never became alike, but both grew more patient and responsible in adulthood, just as research predicts.
Personality and how it is developed involve inherited temperament, genes, unique experiences, parenting, culture, and the roles people take on.
Studies show personality keeps changing throughout life, with people generally becoming more conscientious and emotionally stable, and therapy and deliberate practice can speed meaningful change.
I have seen people grow most when they stop asking “Who am I supposed to be?” and start asking “Which of my traits do I want to strengthen next?”
This week, choose one trait you want to develop and practice one small behavior that reflects it every day.
Frequently Asked Questions
What is personality?
Personality is the relatively stable pattern of thoughts, feelings, and behaviors that makes a person distinct from others.
How is personality developed?
Personality develops through inherited temperament, genes, unique life experiences, parenting, culture, and the roles people take on throughout life.
Can your personality change?
Yes, research shows personality traits change across the lifespan, and a 2017 review of 207 studies found therapy can produce marked, lasting changes.
Is personality determined by genes?
Partly; twin studies estimate that about 40 to 50 percent of differences in personality are linked to genes, with the rest linked to environment and experience.
Pious Clements writes about character, conduct, and the deeper questions of how a life is lived. He is the founder of The Conducts of Life, a site built on the belief that how you behave, not what you achieve, defines who you are. His writing draws from decades of observation, lived experience, and serious thinking about human nature, ethics, and self-development. He writes to be useful, not popular.