In this study, judgments about a person's personality activated different brain areas than emotional judgments alone. For instance, predictions about whether a person might be friendly, outgoing, or adventurous, were very different from simple decisions about happiness, sadness, or anger.
Personality judgments seems to involve areas like the left frontal operculum - an area known to be important for theory of mind (understanding differences between self and others) and decision making.
It makes sense, then that personality judgments are not something that we are born with - grown up levels of theory of mind and decision-making take time.
Much has been written about the development of theory of mind or perspective-taking throughout childhood. Most people know about the theory of mind problems in autism spectrum disorders, but fewer people know about the normal developmental variations, the problems of sensory-deprived populations like the deaf or visually-impaired, and the differences that exist between boys and girls.
One of the milder tests of theory of mind involves faux pas. A faux pas happens when someone says something they shouldn't and violates a social convention (e.g. a person could feel insulted or hurt). In order to "get" at faux pas, one needs both cognitive and emotional empathy. In one study of kids and faux pas, most girls were able to do well by age 9, but the boys could only do well by age 11.
Problems or delays in personality judgment can lead to all sorts of social problems and stresses - one can imagine that it make choosing compatible friends much more difficult, and predicting another person's behavior (like when they might be joking) near impossible.
For most children, improvement in social judgment improves with time, but the early years of school can be painful.
fMRI & Personality Judgments
A Child's Theory of Mind
Theory of Mind Problems in Deaf Children
Frontal Lobe Contributions to Theory of Mind