How is personality formed?

There is the behaviourist approach that believes our personality emerges from our experience and interactions with our environment.this occurs through mechanisms such as classical conditioning, which is where we learn to associate co-occuring stimuli. This can be seen with pavlovs dog experiment and watsons (1925) little albert experiment. Another mechanism is operant condition proposed by B F Skinner, this claims basically we will perform tasks we are rewarded for more often, and ones we are punished for less.
Another approach is the biological approach that claims that our personality is determined by chemicals, hormones and neurotransmitters in the brain. Examples of this is seratonin, which amongst other things, has been linked to happiness, and has been effectively harnessed to create effective anti-depressant medications
There is also the evolutionary approach that posits that we inherit our personality through genes and natural selection. Some evidence does exist for this such as Loehlin and Nicholas (1976) which displayed behavioural concordance between twins.
There is also the socio-cognitive approach which believes that personality comes from thought processing styles and social experience. Evidence from this can be seen in Banduras (1977) bobo doll experiment where he taught aggressive behaviour to children through them observing aggressive behaviour. Other theories in this area also include Baldwins (1999) relational schemas that claim that our behaviour is determined by our relation to those around us
Another, but contentious approach is Psychodynamics, which is widely known as Freud's area of psychology. This approach believes that personality is formed from developmental stages in early life, and the conflict between the ID (desires), ego (implementing reality onto desires) and superego (conscience)
The humanist approach also has views on personality, but provides little in the way of testable theories. This approach claims that people can only be understood through their unique experience of reality, and has therefore brought into question the validity of many cross-cultural approaches to testing personality. Studies such as hofstede (1976, 2011) have attempted to examine the effects of culture in personality, and have found significant effects, but an important thing to note is that whilst means differ, all types of personality can be found everywhere.
When we talk about measures of personality we often measure it with the big five measure (goldberg et al., 1980: Digman, 1989). This measure includes openness to new experience, conscientious, agreeableness, neuroticism, and extraversion.