Temperament definitely does have a genetic component, but also environmental. It is neither nature nor nurture, but a little of both. When I was breeding for pet and show purposes only, I had rats that did NOT need handling, and were just as friendly and easy going as those that were handled from day one. It is about looking for the boldest, least stressed, most way going rats,and go from there.

Katdog that's great! I'm glad they are doing well for you. I keep meaning to go to the shows just to see how things are going, but I never make it. You know about the farm zoo I have! Lol
I have to ask though, Do any of your pedigreed rats have BWR in their lines? If so what names?