Yes, they do in many ways, but when it comes to personality not as much as you may think. Most studies show a stability in personality traits throughout the life span with very moderate change.
And we don’t change according to our individual wishes but uniformly in a pattern dubbed the “maturity principle”. This pattern shows a decrease in impulsivity and Neuroticism (emotional instability) and an increase in Conscientiousness and Agreeableness.
Also, when change occurs, rank order is maintained. That’s to say if you were the most impulsive kid in your family then you are likely to be more impulsive than your siblings as an adult as well, even though your impulsivity has decreased.
All this points to one conclusion: we don’t change as an act of will. It’s more like we are subject to change. The older person may think of himself as having evolved a sense of judgment, social skills and a control over his emotions. In reality, it’s more likely these changes are biological in nature. Being emotionally instable activates the body’s fight-or-flight response which is very energy consuming. As we grow older this state becomes less intense due to lack of energy. And evolution has probably favoured individuals whose impulsivity decreases, since injuries become more dangerous with increasing age.
One particular change that has been discussed a lot is that of women’s Neuroticism, possibly because it fits the old fashion perception of women as hysterical. This may seem like a negative stereotype but there is little denying that young women are high on this trait, although the difference between men and women becomes smaller with time. One psychologist, Sanjay Srivastava , has even concluded that the difference disappears altogether. Looking at his study however (sorry no link, but believe me I have read it), this seems not to be the case. His data goes to 60 years of age and the difference is still clear. But if you extrapolate it does look like it might be the same for both genders at 70, although there is no actual data to support this. And even if there was, the conclusion would be that women are in fact more emotionally instable for almost the entire life span. Still, there are some genuine gender differences supported by the research. Men appear to become less flexible and ambitious whereas women become less feminine.
But none of these changes are very big and they all follow a collective pattern suggestive of biological maturation. Anyone who has been to class reunion probably knows this. So is there no way to change radically, and in a way that breaks this pattern? Yes, there is one way – head trauma. That can make you a completely different person in a totally unpredictable way. So be careful what you wish for.