Social psychologists consider personality to be five traits found across ages and cultures: conscientiousness, agreeableness, openness to experiences, extraversion, and emotional stability. The authors of a new study used a U.S. sample of 1,795 people that assessed their personality traits in adolescence and 50 years later, and then two independent samples, a cross-sectional (3,934 people) and a short-term longitudinal (38 people) to try and add to the debate about whether personality is stable - unchanged over time - or malleable, with the most likely correct answer, which is still a cop-out, being it's both.
They tested how personality might change over 50 years relying on the same data source at both time points and found that broad patterns of thoughts, feelings and behaviors - personality - do change, and this change appears to accumulate with time.
But it is not a drastic change. Those who are the most emotionally stable when young are probably going to continue being the most stable as they age, those who are less conscientious than others from when they were 16 are likely to be less conscientious than others at 66 - but almost everyone becomes more conscientious, more emotionally stable, and more agreeable as they age.
Even gender did not matter. While there were differences in personality at any given time, overall, men and women changed at the same rates across the lifespan.
Damian, R. I., Spengler, M., Sutu, A.,&Roberts, B. W. (2018). Sixteen going on sixty-six: A longitudinal study of personality stability and change across 50 years. Journal of Personality and Social Psychology. DOI:10.1037/pspp0000210