I know it is possible russian scientist showed it was possible to breed out anger(in foxes at least). I watched a documentary on it, they used silver foxes. They bred out the anger in about 10-15 generations, they wanted to see if the mothering had anything to do with it so they gave happy moms angry pups, they stayed angry. The angry moms got good pups n they keeped the nice-ness. They stepped it up n did embyro swaps n the resulter were the same. But the weirdest thing wast they happy animals changed in apperance after a while. Their legs got shorter, they eyes changed colours, their furs went from charcoal grey to whites, blacks, tans, silver to almost blue and started to develops patterns like blazes n muzzles. It was weird but its possible just will take a very very very long time and they had alot of test animals in the project like 2500 foxes picked from mills at random.