I understand your point, it's just that one of the "arguments" that the pit bull loving hand wringers use against banning the breed is that banning the breed is like banning a variety of gun. Just ain't so for the very reason you mentioned. Guns don't attack all on their own. And I don't buy their crap that "it isn't the dog it's the owner." If dogs can be bred for different appearance, they can also be bred for different levels of aggressivness.
Bingo!!! They are bred for violent aggressive behavior.
Saw a really interesting documentary on canines. They included a segment on Soviet efforts to breed tame silver foxes. From a captive population of approximately one thousand foxes they began breeding. The first captive generation they had about 1% that showed indifference, neither fear nor aggression, toward humans. They bred these with each other and in two generations had tame silver foxes. The really curious thing was that other physical traits in the silver foxes changed as well (although not specifically bred for these traits, they were just concentrating on the temperament), and the resulting foxes looked more 'dog-like'.
Anyone that thinks aggression is not a genetic predisposition in breeds is simply uninformed.