I don't think that's the only line - I am pretty introverted but like having a place outside of my home where I can work. It's enough of a "default mildly social" situation to not feel isolated or restless if I want to do something like watch a movie or read at night (and I have a partner but that's not the same). I'd say most of the variability can be explained with three questions 1. Do you have a long commute? 2. Do you have a nice working environment at the office? 3. Do you have kids?