“People can fundamentally change who they are, even late in life.”

Research is shifting on whether adult personality is fixed. A July 2026 study of about 167,000 people found that traits like conscientiousness and agreeableness keep shifting across adulthood, and that people underestimate this. Skeptics point out that the shifts are gradual and modest, and that people tend to keep their place relative to others: a shy person usually stays shy, even as they mellow with age. Whether that counts as “fundamentally” changing depends on what you mean. Gradual drift may not be a change in who you are, and a dramatic reinvention, like the stories behind recovery or religious conversion, may be rarer than we like to believe.

Amanda Wright, Wiebke Bleidorn, and colleagues (2026 study in Communications Psychology, lean toward agreeing): their paper is titled “Personality traits are less stable than people think.” They found that traits keep developing across adulthood and into old age. Their own caveat is that the findings describe averages across large groups, not what happens to each person. Paul Costa and Robert McCrae (psychologists behind the “set like plaster” view, lean toward disagreeing): in their 1994 chapter “Set like plaster? Evidence for the stability of adult personality,” they argued that core traits are largely settled by about age 30. Even researchers who find change tend to agree that people mostly keep their relative standing: the most outgoing in a group usually stay the most outgoing as they age. Wiebke Bleidorn and colleagues (2022 meta-analysis, middle ground): found that personality is fairly stable but never perfectly so, and that people differ widely in how much they change. A 2026 paper in the European Journal of Personality adds that evidence on whether big life events, like marriage or loss, change personality is still inconclusive.