Its hard to know how a dog will behave when it grows up even when it is treated well.

Some dogs are just so gentle natured and some can take an instant dislike to some people, what or how that happens - I do not know.

I love my dogs, look after them and always have two, but if I had one that became aggressive I would not hesitate to have it put down, its just not worth the risk especially when we are around children.

I believe it is about 70% owners fault and 30% the dogs. I say this based upon the kind of people that are more likely to own a Pitbull for example. Usually the people that own these dogs are people that are likely to bite as well. The dog gets a large part of its' attitude from their owners.

Now for the 30% on the part of the dog. Certain breeds of dogs were breed to do jobs like herding livestock and this is an inherited trait within that breed. For over 40 years I've been around Border Collies, they will bite someone that is running. This is the herding instinct in this breed. These dogs are normally very, very friendly and when they bite, they do it to correct an unwanted behavior in the humans (such as running). These dogs are more nippers than aggressive biters. All they want is to control the situation and then are done. They get along with kids very well and are generally extremely tolerate of everything but running as mentioned. Kids have to be advised not to run and then there is no problem.

You should need a $10,000 permit to own a Rottweiler or pit bull. It should also need to be renewed yearly. But seriously, there is no reason for a civilized person to own a pit bull or Rottweiler. Sure, not all dogs of those breeds will maul a small child to death, but they have the highest tendency to do so. They require the least amount of owner mistreatment/negligence to become violent. People who sympathize with these breeds are the same as those women who fall in love with prisoners.