I think another variable that could influence both the dependent and independent variable is location. Meaning that if you grow up in a location that fosters a sense of closeness and community, then you are more likely to grow up less synical and more trusing. On the other hand if you grow up in a more harsh location that isolates individuals, then they might grow up and be more closed off and less able to open up to others, even people close to them.
I agree that location differences definitely tie in as factors in how well adjusted and individual is later in life. Different locations are defined by differing cultures and different circumstances that would require different personalities and different dispositions.
