I don't agree with this at all. I know of hundreds of backyard flocks with varied breeds that co-exist fine. In fact, I can't think of any first time chicken owner who bought a flock of all one kind of chicken from me. EVERYONE gets a mixture of breeds and it works out fine. There are very few breeds that are genetically mean (gamefowl and Leige Fighters - maybe), the vast majority do fine together, especially if they are raised as a group. We tend to project human qualities onto our pets and look for behaviors that support our theories and ignore those that don't. They are birds, not people. They can't look in a mirror, then at another chicken and think "that hen looks different from me - I hate her". Humans are peculiarly prone do doing things like that, birds have no inborn prejudice and they don't even learn them easily.Wise words. They are wise words for humans, however, not for chickens. Having a variety of breeds will definitely give you spice, just not the good kind. Even the miniscule differences between birds will be enough to single them out. If you have two of each breed (for example), you'll be creating three sub-groups