The study of how the social environment affects an individual's behavior and personality.

So, the core of the study is the behaviour and personality - and this is usually studied by psychology. Therefore we can guess that we are looking for a branch of psychology.

This branch is social psychology - it focuses how the society (social environment) influences this behaviour.

It should be at the center of any map going vertically: the prime meridian, as it passes through greenwich,  england, is considered 0 degrees longitude