Maybe I just got lucky with mine. I separated the original group I got into 2 colonies. 1 for color and 1 for temperament. These same rats from the breeder I got them from will rush across their tub and maul his tongs. Even the tub selected for color is friendly. They'll rear up like a hamster and squeak qith their eyes closed, but will not bite. All are very curious. I'll see if the "temperament" tub gets progressively more outgoing, but I also think part of it is how you interact with them.

Breeder I got them. From uses tongs and admittedly isn't very nice to them. I started off handling them before they had their first litters, and gently scoot them off their babies. They're neat little critters to work with, and I have a couple that will let me scritch their heads while they close their eyes and stretch out their legs