How malleable are personality traits, if at all?

I think personality traits can be changed, but I wonder if it's more likely that people who want to change make a deliberate effort to do so (rather than it just sort of "happening" naturally).

Anecdotally, I (very introverted) went through a period in college where anyone who met me would have called me an extrovert. I didn't have a lot of friends as a kid and went to college with the intention of changing that. It worked, but it was only about two years before I got sick of acting all the time and reverted back to my introverted self. I've wondered whether stuff like this still "counts" as an actual personality change, or is it just covering up the real you?

I think they can definitely be changed but obviously much harder to move than simple opinions on certain topics.

I think something like a life altering event could definitely shake up your core beliefs enough to make you more motivated.

If you want to go completely extreme there have been cases of people with brain injuries who turn into completely different people, but I feel like still short of actual physical changes you can ultimately change quite a bit.

There are certain traits that seem to be inherited. One is having high levels of Cortisol, causing people to be highly sensitive. I've seen it in children from birth, and one psychologist has studied it in depth, Elaine Aron.

Of course as knowledge of chemical pathways increases, we're always learning that more and more traits can be altered artificially. An older and more general term that I like is 'predeliction' (a preference or special liking for something; a bias in favor of something.) Carlos Castaneda uses this term getting at more an innate tendency to behave in a certain way. It carries a connotation of less changeable nature than the modern 'personality trait' does. Very old fashioned I suppose, but Castaneda was more a poet than he was a sociologist.

Personality is a fun subject for psychology research and there is a large number involving published each year.

Check out this meta analysis regarding personality change over time:

https://scholar.google.com/scholar?hl=en&as_sdt=0%2C48&q=personality+traits+change&btnG=#d=gs_qabs&p=&u=%23p%3DhXhc-vgtcYkJ

As has been noted elsewhere, there are very few data to support this position (Roberts et al., 2005). The few longitudinal studies of twins have shown that childhood personality change appears to be largely genetic, whereas in adulthood genetics has only a small influence over personality change (Plomin & Nesselroade, 1990). In adulthood, the largest estimate of the heritability of personality trait change is around 30%, with the average being much lower (McGue, Bacon, & Lykken, 1993). This indicates that environmental factors play a larger role in personality trait change in adulthood than do genetic factors. Moreover, the findings from the present study showing that patterns of change were associated with cohort would also contradict the notion that personality trait development is independent of environmental influences. Thus, there is little evidence to support the idea that development of personality over time is independent of environmental influences. On the basis of our analysis of the evidence to date, we believe that life experiences and life lessons centered in young adulthood are the most likely reason for the patterns of development we see in this meta-analysis, especially the increases in social dominance, conscientiousness, and emotional stability (Roberts et al., 2005). Specifically, the universal tasks of social living in young adulthood, such as finding a marital partner, starting a family, and establishing one’s career, appear to be candidate experiences through which people also experience increases in such traits as conscientiousness and emotional stability. As all dominant cultures support if not promote these activities, they may be the catalysts for the widespread pattern of personality trait development found in adulthood and across cultures (Helson, Kwan, et al., 2002; Roberts et al., 2005).

Really the whole section:

Why Does Personality Change in Adulthood?

Is a good read involving this discussion.

One thing that's important to note is that personality has most popularly been operationalized with the Big Five factor model with each of:

1. Openness
2. Conscientiousness
3. Extraversion
4. Agreeableness
5. Neuroticism

Being made up of many, many different facets/traits.

You can take a free Big Five personality test that is both reliable and valid from here:

https://www.personal.psu.edu/~j5j/IPIP/