As a lifelong dog owner, the owner of the dog is who trains them to be more aggressive than what they already are predisposed to be. Dogs that are built for working farms and everything (Rottweilers, Mastiffs, German Shepherds, Pitbulls, etc.) have a tendency or inclination to not only please their masters but to protect the territory. Pitbulls are medium build but muscular and extremely athletic, and thus, can be a nightmare when in attack mode due to how territorial they are. I've owned them and of course, they were extremely dangerous to anything or anyone not living every day in the household, but for us in the family...... great family dogs.
Pitbulls get a bad rep because of two reason, in my opinion....... one, because of the Hip-Hop culture (overly stereotyping Black males and a distorted masculinity that Pitbulls equate manhood)..... two, because the majority of publicized attacks are done by them. All dogs are capable of turning against their owners.