rockm

Spoonman,

Rotties were originally bred to herd and handle cattle. Pit bulls were developed to fight in dog pits. The Doberman is the only one on your list that was developed specifically to protect human beings. It's named after a German tax collector that originally developed the breed after being threatened while doing his job. The genetic traits that were bred for to serve each job are very different and really can't be lumped together.

Genetic predisposition to "violence" is a very hard thing to nail down. In any case it forms only a small basis for behavoir. Again it's up to the owner to shape the dog. Dogs do what they live. Any dog can be trained to be "violent"--leave a Golden retriever alone outside, tied up to a stake, allow it to become spoiled and dominant in your house, let your kids tease it, praise it when it growls at other dogs and people etc. and it will become pretty agressive and dangerous. It just won't be able to sustain an attack as long or do as much damage as a stonger breed.