The accumulating evidence shows impressive stability in personality differences

From The Hierarchy of Consistency Revisited.

Science can be hard. Astronomy required telescopes to study the universe. Psychologists need longitudinal studies to examine stability of personality and personality development. The first telescopes were imperfect and led to false beliefs about canals and life on Mars. Similarly, longitudinal data are messy and provide imperfect glimpses into the stability of personality. However, the accumulating evidence shows impressive stability in personality differences. Many psychologists are dismayed by this finding because they have a fixation on disorders and negative traits. However, the Big Five traits are not disorders or undesirable traits. They are part of human diversity. When it comes to normal diversity, stability is actually desirable. Imagine you train for a job and after ten years of training you don’t like it anymore. Imagine you marry a quiet introvert and five year later, he is a wild party animal. Imagine, you never know who you are because your personality is constantly changing. The grass on the other side of the fence is often greener, but self-acceptance and building on one’s true strength may be a better way to live a happy life than to try to change your personality to fit cultural norms or parental expectations. Maybe stability and predictability aren’t so bad after all.

The results also have implications for research on personality change and development. If natural variation in factors that influence personality produces only very small changes over periods of a few years, it will be difficult to study personality change. Moreover, small real changes will be contaminated with relatively large amounts of random measurement error. Good measurement models that can separate real change from noise are needed to do so.

One of the Utopian dreams is that man can be reeducated into New Man.

That dream is slowly being undermined. We are discovering that IQ is substantially determined by genes and is stable over adult life. You have the hand you are dealt.

Similarly with all sorts of other physical and behavioral traits. Similarly, as mentioned above, with psychological traits (the Big Five).

You are who you are and not easily susceptible to change to make you a better model. If you are a Utopian statist, that's pretty disappointing. If you glory in the rich diversity of humanity, there is nothing to be concerned about, at least philosophically.