People like Victor Meldrew may be the exception rather than the rule
People get nicer and more generous as they grow older, a study suggests.
Researchers in the United States have found that people's personalities change as they age and in most cases for the better.
The finding contradicts previous studies, which have suggested personality is largely set in stone by the time people reach their 30s.
Some scientists believe personality traits are genetically programmed to stop changing by early adulthood.
But this latest study suggests this is not the case.
Researchers at the University of California at Berkeley based their findings on a study of more than 132,000 people between the ages of 21 and 60.
They each took a personality test posted on an internet website. The researchers selected only those living in Canada and the United States.
The participants took the Big Five Inventory, a test used to measure what psychologists refer to as the "big five" or main parts of human personality.
These are conscientiousness; agreeableness; neuroticism; openness; and extraversion.
The researchers found that concientiousness increased throughout life and particularly during people's 20s. In practice, this means that people become more organised and disciplined.
The study also suggested that agreeableness improved throughout life and particularly during people's 30s. In practice, this means they become warmer, more generous and helpful.
The researchers found that neuroticism declined with age in women but did not change in men. This suggests women become more stable as they grow older.
The study also revealed that both men and women become slightly less open with age and that women become less extraverted as they grow older.
Men did not show any signs of becoming less extraverted with age.
Overall, young women are likely to be more neurotic and more outgoing than young men. However, this difference levels out with age.
The researchers said the findings showed that personality can change throughout life.
Writing in the Journal of Personality and Social Psychology, they said: "The findings in this article suggest that people continue to mature well into adulthood."
They suggested a variety of factors may influence personalities, including genes and people's experiences.