What is defined as psychological maturity?
Psychological Maturity is socialisation that occurs until approximately adolescence. It is the maturing process that makes humans able to understand what is acceptable and what is acceptable thought – not just actions. It effectively narrows down what is “normal” and changes the way the brain operates to compensate for the culture’s norms, becoming more efficient at carrying out these operations and prioritizing them.
From where is it attained
Rationally the only source of psychological maturity (not brain growth) is from the environment, meaning other humans. This is because if the brain already contained the information from the environment it would be accustomed instantly, and psychological maturity in society would change slowly if at all, and not reflect the society’s changes. Not only this but psychology over different cultures would be remarkably the same and children of other ethnicity or genetic make would be unable to change their psychological maturity by maturing in a different culture.
This also means the process itself is one similar to some parts of evolution.