There is nothing scientific in your answer. All of the pit bull's violent "nature" was trained and bred-in by people, on purpose. The breed's name comes from a

There is nothing scientific in your answer. All of the pit bull's violent "nature" was trained and bred-in by people, on purpose. The breed's name comes from a violent game involving pits and bulls which you can investigate. As long as we continue to breed-in, train for, and encourage this behavior, it's what we will get. Modern dog behavior science now understands that dogs communicate with sophisticated body language and react to each others' communications by releasing hormones that affect the entire body. When the dose reaches a high enough level, the dog is left with few choices as to its reactions. THAT part is built-in. But humans can and must manage the situations where we place these dogs and the behaviors that we model for them. We've done a terrible job of that and it shows in the breed behavior.