Personality is a combination of Nature and Nurture.
The Natural (genetic) parts are Physique, Intelligence,
and Temperament. The Nurtural parts are Environment,
Culture, sub-culture, childhood environment, schooling,
parental influences and experience.
Add a measure of Luck and there you have it.
This is but one of many models of Personality; not
everyone will agree with it, but it's as good as any other.