After a comrade suggested the idea that the human brain is just as adaptable and similar across all humans; I think that "personalities" are just social traits adapted to the material conditions of the human environment.
A human developing in the capitalist environment develops greed (as capital necessitates) merely for survival; not as a default trait.
In socialist and communist environments, humans develop collaborative traits.
Applying this idea further, the characteristics of how much work people put in is influenced by the environment; being stuck in a petite-bourgeois environment means that a person would develop laziness as a result of lacking the need to work.
In a socialist or communist economy a person would be more willing to work; as a result of the proletariat being the ruling class and thus treating workers well.
So technically, I could change my lazy ass into a worker just by changing the environment to a socialist one.