Ask people how much their personality will shift over the next year and they will tell you: not much. Ask how much it has shifted over their lifetime and the answer is similar. Research published in 2026 in Communications Psychology suggests both answers are wrong — and wrong with remarkable consistency. Personality change turns out to be one of the things humans are worst at estimating about themselves.
When researchers compared what people predicted against what longitudinal data actually showed, participants underestimated year-to-year change roughly 90% of the time. For lifetime change, they were wrong in 100% of the comparisons examined.
What the personality change research found
The study combined two things that are usually kept apart: public beliefs about how stable personality is, and empirical data from long-running studies that have actually tracked the Big Five traits over years.
The headline comparison is striking. Population-average Big Five traits — openness, conscientiousness, extraversion, agreeableness and neuroticism — changed as much as or more than many health, financial, psychological and social measures over the same periods. Personality, in other words, is not the fixed point around which a changing life revolves. It moves about as much as the rest of it.
Yet people treat it as unusually stable. The perception gap was not a minor calibration error; it was systematic and it ran in one direction. Nobody was overestimating how much they would change.
Why we are so confident and so wrong
The survey data does not explain the gap, so what follows is interpretation.
The most likely culprit is how memory works. You do not have access to your former personality; you have access to your current memory of it, reconstructed with today’s self as the template. That reconstruction smooths out change, because the remembering is done by the changed person.
Identity probably plays a role too. Believing you are fundamentally the same person across decades is load-bearing for a coherent sense of self. Noticing that you have become measurably less neurotic or more conscientious than you were at 25 is, in a small way, noticing that the person who made your major life decisions is not quite you.
A separate 2026 study adds a useful wrinkle: family and close friends often notice changes in someone that the person themselves misses. The people watching from outside are not running the same reconstruction.
The genetics finding that complicates the picture
In parallel, a large 2026 genome study substantially expanded what is known about the heritable component of personality, identifying more than 1,000 genetic variants associated with Big Five traits. The jump in resolution was dramatic: variants linked to conscientiousness rose from 3 to 131, and for neuroticism from 224 to 706.
It would be easy to read these two findings as contradictory — personality is genetic, but personality changes. They are not in conflict. Heritability describes why people differ from one another at a given moment. It does not mean a trait is fixed across a lifetime. Height is strongly heritable and also changes enormously between ages 5 and 25.
The honest summary is that genes influence your starting position and your range, while time, circumstance and effort move you within it. Our guide to the Big Five traits covers what each dimension measures.
This distinction matters because the two findings landed within months of each other and were widely reported side by side, often with headlines pulling in opposite directions. A reader could reasonably come away believing both that personality is written in DNA and that it drifts constantly. Both reports are accurate; they are simply answering different questions, one about variation between people and the other about variation within a person over time.
What these studies cannot tell you
Several limitations deserve attention.
These are population-average findings. That average conceals wide individual variation: some people genuinely do change very little, and the study cannot tell you which group you are in. “People underestimate change” is a statement about the aggregate, not a prediction about you.
Big Five measurement relies on self-report questionnaires. If your standard for what counts as “organised” shifts as you age, your score can move without the underlying behaviour changing — a known problem in longitudinal personality research.
The genome findings identify statistical associations across very large samples. Individually, each variant contributes a vanishingly small amount. Having 706 variants associated with neuroticism does not mean anyone can read your neuroticism from your genome; the predictive power at the individual level remains weak.
And none of this establishes causation about what drives change. Knowing that traits move is different from knowing which life events move them.
What follows practically
The most useful implication concerns the predictions you make about yourself.
Be sceptical of “I’m just not that kind of person.” Stated about a trait, this is a forecast, and forecasts of personal stability are the ones this research finds systematically wrong.
Treat personality test results as a snapshot with a date on it. A result from five years ago is a historical document, not a current description. Retaking a Big Five assessment periodically is more informative than treating one result as your permanent type.
Ask people who know you well. Given that close contacts appear to notice changes the person misses, outside observation is genuinely additional information, not just a second opinion.
Do not over-plan around your current traits. Career and relationship decisions made on the assumption that you will want the same things at 45 that you want at 30 rest on a stability assumption the data does not support. See our look at what 30 years of Big Five research says about personality at work.
Frequently asked questions
How much does personality actually change over a lifetime?
Enough that population-average trait change was comparable to or larger than change in many health, financial and social measures. The research emphasises that people underestimate it rather than fixing a single number everyone should expect.
If personality is genetic, how can it change?
Heritability explains differences between people at a point in time, not permanence within a person. A trait can be strongly heritable and still shift substantially across a life.
Can I deliberately change a personality trait?
These studies document that traits move; they do not test intentional change. Other research suggests deliberate change is possible but slow and effortful. Treat this as an open question rather than a settled one.
Does this mean personality tests are useless?
No — it means they are time-stamped. A Big Five profile describes you reasonably well now and progressively less well as years pass.
Which Big Five trait changes most?
The coverage of this research emphasises overall underestimation rather than ranking traits. Longitudinal work has generally found conscientiousness and agreeableness tend to rise with age while neuroticism tends to fall, but that is a broader pattern than this specific study.
The wider point
Personality psychology has spent decades arguing about whether traits are stable. The 2026 work reframes the question: traits are moderately stable, people believe they are far more stable than that, and the gap between those two facts shapes a lot of decisions.
The practical upshot is modest but real. You are probably not going to be quite the same person in ten years — and you are also probably going to be surprised by that, because almost everyone is.
Further reading: MedicalXpress on the personality change study and Nature on the Big Five genetics research.
