In dealing with the public for a living I found that some are just not people persons. If that makes sense. They are reserved, don't really talk unless talked to and don't start random conversations unless they feel comfortable with the other person and then the conversation is of their interest. I have a client who is an Accountant, highly intelligent, well respected and has a well established business. He's got a dry sense of humor, is on the quiet side but knows his job well inside & out. Doesn't the saying go.....Different strokes for different folks.