Pit Bulls are not all that mean really. The reason Pit Bulls become mean is because of their surroundings and their owners who make them mean.
I've been around mean Pit Bulls and I've also been around some really nice loving Pit Bulls so it depends on the Pit Bull and who've they been around and how they were treated.
If they're around a loving family then they will most likely turn out to be a good non aggressive dog.
Let the Pit Bull grow up in a family or around a person who's mean to the dog then it could become aggressive but that also goes for other breeds of dogs as well.