Does an elastic band stretch better in a hot environment than in an icy one? When I read about this subject I often find omissions of environmental effects, especially during childhood, and how they effect those senses of intro/extroversion. I don't get why. I grew up around people who I just didn't jive well with. I always wondered if I'd be an extrovert if I had grown up in a talkative family that brought nice friends around that I might have enjoyed talking to. I also didn't get to keep friends as we moved countries often and I often believe that is a big factor as well. But who knows. Indeed I can now only stretch my personality to a point.