While I agree somewhat that a dog is the product of how it is raised by its owner, I disagree that breed has nothing to do with agression. Pit bulls, terriers, dobermans, German sheperds, and Akita were bred to be agressive. That was the direct intent of creating the breed. In the case of pit bulls and akitas, those breeds were created for the sole purpose of being fighting dogs. You will have some mellow dogs within those breeds, much the same way you will have agressive dogs in breeds like beagle, hound, or retrievers.
But, agression is breed into these pit bulls, akitas sheperds, and terriers....there is no getting around it. The owners can train them to go against their nature and be docile or they can encourage them to follow their aggressive nature.
But, no matter how docile you train a pit bull to be, it is by nature, an agressive dog and one day may snap and rip a child's face off.