Why Do We Become Different People Over Time?

“The only person you are destined to become is the person you decide to be.” - Ralph Waldo Emerson

Personality isn’t set in stone. Throughout what feels like a single lifetime, many of us feel that we’ve reinvented ourselves - or at least, that the same self from years ago would barely recognize who we’ve become. Modern psychology confirms this subjective experience: while some core parts of our identity stay consistent, the rise and fall of circumstances, values, and emotions can transform how we think, act, and feel.

1. The Dual Nature of Identity: Stability & Change

Genetics accounts for roughly 40-60% of what makes us “us”, with the rest shaped by environment, experiences, and choices.
Big Five personality trait studies show rank-order stability (who is more extroverted than whom) remains fairly constant into adulthood (correlations r ≈ .66-.80), but mean-level changes (how extroverted we are on average) happen steadily across the lifespan.
Generally, as people age: conscientiousness and agreeableness increase; neuroticism, openness, and parts of extraversion gradually decline.

Key takeaway: We maintain personal “rank” over time, but the average level of traits - our energy, stability, and openness - shifts in predictable ways as we age.

2. Life Transitions Rewire Who We Can Be

Social Investment Theory argues that life stages like transitioning from school to work or starting a family prompt long-term shifts in personality. New roles require more stability, discipline, and emotional control - and we often rise to meet them. Gains in conscientiousness and emotional stability are typical responses.
Even brief periods like military training or a major life event can produce lasting changes in personality - sometimes in unexpected directions.

Real-world example: A quiet college student becomes assertive when she becomes a team lead at 28. The “role” shaped the trait - and amplified it over years.

3. Moods, Context & Daily Variations

Studies of introversion/extroversion reveal that context matters. Walter Mischel’s classic research shows traits like friendliness or temperament fluctuate based on mood and environment - not permanent labels
Even neuroticism - linked to anxiety and moodiness - varies with short-term emotional states. Stress, sadness, or the right environmental trigger can temporarily raise levels, altering behavior and feelings.

Insight: Personality isn’t only “who you are,” but sometimes - “who you are being right now.”

4. Your Brain’s Narrative: Who You Tell Yourself You Are

Narrative identity theory shows we all craft a personal life story. Major events, relationships, and roles become plot points in an evolving story rather than fixed scripts. That story can reshape how we see ourselves - and lead to real behavioral change. Older adults often report being “unrecognizable” to their teenage selves - even when core traits stayed similar.
The New Yorker’s essay “Becoming You” reflects that personal stability is less biology, more memory and meaning - the stories we choose to preserve or discard shape how we change over time

5. Mindset and Intention: A Willingness to Be More

Stanford psychologist Carol Dweck’s “growth mindset” concept shows that believing in our ability to change can literally unlock personal transformation. Just a single word - “yet” - turned “I can’t” into “I can eventually” in experimental studies, boosting motivation and effort.
A landmark 2020 intervention study confirmed intentional trait change is possible: participants using a growth mindset mobile coaching app improved traits like conscientiousness and openness within weeks - and maintained gains three months later.

6. Happiness and the Hedonic Treadmill

The concept of a “happiness set point” suggests most of us return to baseline levels of contentment after life’s ups and downs. But that set point isn’t fixed for everyone. Traumatic events like the loss of a loved one or job impact long-term well-being - sometimes permanently - unless intentional coping strategies are applied.
Certain personality traits - like optimism, resilience, and conscientiousness - predict better adaptation and ability to alter that baseline for the positive.

7. Why We Change: A Summary Table

Driver	How It Changes Us	Typical Outcome
Genetics (40–60%)	Sets baseline irritability/emotional reactivity	Levels of neuroticism, extraversion
Life transitions & roles	Demand new habits and ways of relating	Increased stability, responsibility
Mood & environment	Influence moment-to-moment behavior	More fluctuation in recorded traits
Narrative identity	Changes in how we interpret our past & direction	Reframing meaning → new personal goals
Intentional mindset/training	Motivated effort to shift how we act/feel	Measured gains in Big Five traits
Major trauma or loss	Resets baseline over time	Chronic shifts in well-being (positive/negative)

Transform or Stay the Same? It’s a Choice

By understanding the science, we see that while genetics and history shape us, greater change is not only possible - it’s normal.
Mindset shifts, new roles, intentional growth practices, and conscious reframing can lead to sustained changes in who you are and what you feel.
Even into your 70s and beyond, personality remains plastic and growth stays possible. Personalities may stabilize by 40 - but aspirations and meaning evolve well into old age.

Final Thoughts: Can You Become Someone New - and Should You?

Yes: you already are. Change isn’t about erasing your past self; it’s about building on it, making additions rather than overwriting. Your values, skills, and emotional life can all evolve, especially when your mindset matches your desire for growth.

To anyone wondering, “How did I get here?”, remember: it’s not just who you were - it’s what you did along the way.

Mohamed Dosou™

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