As I have said in a prior thread
I had a pit bull that I saved from fighting, she was six months old when I got her and I will swear she was the ultimate best dog you could ask for. I would have trusted her with my son from the day I brought him home from the hospital. She very easily could have turned on me as she WAS a fighter, her parents were fighters and her grandparents were fighters, so it was in her blood. She welcomed cats in to our home, she also welcomed another dog in to our home. She was seriously the best dog you could have.
There isnt a rule about what dogs can and cant turn, all dogs are capable of biting. It appears the media just likes to focus on certain types of dogs. When we were growing up I remember, Doberman Pinchers were the bad dog, then it went to German Sheppards, then Rotties. All dogs can turn, not any specific bread.
I guess my dog could have turned because of how she was brought up for those six months, but as any dog that is abused, I would guess that could happen with any breed.
I have had interactions with many types of dogs and when the time comes for us to get another dog, I would love to have another pit bull so my son can grow up with a great and loyal companion.