Does Your Personality Change Over Time?

Facebook memories can be cringeworthy.

 

Few things are more likely to provoke a shudder and scrunched up face than having something ridiculous you posted years ago pop up on your screen.

 

But while the Facebook memory function should almost certainly be abolished forever for the greater good, those memories – both the ones that make you cringe and the beautiful ones that inspire joy and smiles and nostalgia and gratitude – reflect the journey of our human experience.

 

Were I to ask if you were the same person ten years ago, you might say no. Perhaps you see yourself as having transformed over the years.


But what if I asked if you had the same personality?

 

Because I deliver training on behavioural profiling, I’m often asked whether personalities can change over time. While, of course, childhood and adolescence is considered developmental, people want to know if our traits change; not just in our developmental stages of life, but throughout the lifespan.

 

It’s a fascinating one that touches the very core of human existence: Are we a singular, static ‘self’ or do we evolve and change at our core throughout life?


Or maybe a more lighthearted take: Am I going to become more assertive and confident as I get older? (Because that would always be nice).

 

The brain and human behaviour are wonderful things because we are always learning more about them. They’re a bit of a mystery wrapped in an enigma, with fields from evolutionary psychology to biology to behavioural science all striving to uncover their secrets.

 

For a very long time, the commonly held view was that personality doesn’t change. I remember reading the long-standing theory that personality ‘locked in’ at around 30 years old. After 30, you were done. Finito.

 

When I was doing a certification in DISC behavioural profiling, I was taught that the personality doesn’t change, except in response to rare circumstances like a traumatic event or onset of a mood disorder.

 

But these ideas are being challenged in recent research. The old idea of “completing” our personality at 30, and the very Freudian concept emphasising childhood in dictating our traits are giving way to the realisation that things are a touch more complex than we thought.

 

Personality development 

Perhaps it helps to start with how personality develops in the first place.

 

When it comes to personality, the most well-known studies on the topic of individual differences are twin studies, using both identical and fraternal twins to understand the proportional influence of environment and genetics on personality. From a number of papers assessing the heritability of personality, most now generally theorise that about half of our personality comes from genetics[1]. The other half is attributed to external environmental factors, particularly the “non-shared” or unique environment, rather than the home/shared environment[2].

 

(This makes sense if you consider how many siblings you know who are vastly different people.)

 

At the same time, the research around heritability of traits is complex and continuing. There are suggestions that it’s more intricate than this 50:50 scenario because the statistics don’t account for individuality. Ongoing studies have explored the complex gene-environment dynamic and concluded the moderating effect of certain factors – for example, the parent-child relationship) to be more significant than we may have previously given them credit for[3].

 

This general structure is useful for the purposes of our question. If around half of our personality is inborn, and the rest is acquired through individual experiences, one could infer that personality leaves at least some room for dynamism.

 

But does it keep developing over our lifetime, like a grand old tree that never stops growing? Or maybe it’s more like that cactus I used to have in my office: Sometimes it blooms a little flower or two, but it always reverts to being the same old cactus. Slight changes are always temporary.

 

Recent research sheds light on the matter.

 

I have done my best to nut it out, and while I am not a scientist, this is what I’ve come up with. (Scientists, feel free to chime in if I’ve misinterpreted.)

 

Does personality change across the lifespan? 

One 2019 study measured participant’s personalities across fifty years. They found, overall, that “personality has a stable component across the lifespan, both at the trait level and at the profile level, and that personality is also malleable and people mature as they age.”

 

Diving in a little more, the researchers found, over the ten personality traits assessed, that “on average, on any given trait, about 40% of the people in the sample showed reliable change, whereas 60% did not.”

 

With individuals, they found that 97.9% of the participants reliably changed on one or more of the ten traits in 50 years. Generally, people increased in their traits, with the exception of impulsiveness, which went down over the 50 years.

In the journey from age 16 to 66, people increased in:

·      Calmness and Self-confidence (facets of Emotional Stability)

·      Mature Personality and Tidiness (facets of Conscientiousness)

·      Leadership (a dominance facet of Extraversion)

·      Social sensitivity (a facet of Agreeableness)

While social dominance (like assertiveness) increased over time, social vitality (like gregariousness) increased a bit in adolescence then decreased slightly in older age.

 

Of course, as individuals are inclined to do, some people changed more than others, while some changed less. Overall profile stability averaged out at .37, which the researchers equated to 70:30 odds of someone staying in the same personality “zone” across the fifty years. (The same “zone” being above or below the median).

 

This idea of cumulative change also aligns to a 2016 study. This research found that ages 20 to 40 were the key period for mean-level personality-trait change. However, it was suggested that personalities could change in some ways all the way through our lives: As the 2019 study states, “…there is evidence for stability in personality traits across the lifespan, while at the same time there is evidence of change presumably resulting from life’s trials and tribulations.”

 

The changes in both studies largely aligned with the ‘maturity’ principle: That we mature in a positive way over time. In other words, as people get older, they tend to get a little more stable, reliable and confident.

 

Maybe we really are more like the grand old oak tree.


  

Some popular self-development seminars have taken this idea of change and ran with it. Some swing to the other side of the pendulum completely: Suggesting that we all completely ‘create’ ourselves. (This kind of rhetoric, to me, can be a little over the top. I’d prefer language around embracing your authenticity, and working on positive behavioural changes – not becoming an entirely ‘different person’. I like personal development speakers and courses that take the latter stance.)

 

So, to our question. At this stage, the most true answer appears to be that while we have elements of a ‘true self’ that stay more rigid, we also experience relatively predictable, slow levels of change in personality over time.

 

This is as encouraging an insight as it is fascinating. It allows us the reassurance of knowing we have some levels of baseline ‘self’, but also the freedom to choose our behaviours and the knowledge that we aren’t necessarily the exact same persona 10, 20 or 50 years from now. We know that we’ll probably be pretty similar relative to our peers across our life, but also that there is wiggle room for bits and bobs to recalibrate and mature.

 

There’s also something heartening about the maturing principle, and knowing that all the ridiculous people you know (maybe including the self) are capable of growing up a little bit.

 

TL;DR: At this point, it seems that for most people, some personality traits remain relatively stable, while others tend to mature positively across the lifespan. You’re still you at 60 compared to 20, but you’re probably more mature in a number of ways, and small gradual changes can occur across the decades. The research continues!


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[1] Krueger, R. F., South, S., Johnson, W., and Iacono, W. (2008) The heritability of personality is not always 50%: Gene-Environment interactions and correlations between personality and parenting. Journal of Personality, 76(6), p1485-1522.

[2] Bouchard, T., & Loehlin, J. (2004). Genes, Evolution, and Personality. Behavior Genetics, 31(3), 243-273.

[3] Krueger, R. F., South, S., Johnson, W., and Iacono, W. (2008) The heritability of personality is not always 50%: Gene-Environment interactions and correlations between personality and parenting. Journal of Personality, 76(6), p1485-1522.