Well, each dog has it's own personality, what you're thinking, is that it's bread into the dog to be semi aggressive or aggressive all the way around, however, dogs that are bread to be mean and are made to be mean can be changed with proper training.
Just think, if a person is born from 2 parents that are drug addicts, and the person becomes a drug addict, can't that person change? Dogs are just like people. My 2 dogs that I currently own were once used for attacking other animals, including dogs. They were breed just for fighting. Tyson was fought for about 3 yrs and Peaches was used for fighting before I got her. They will attack any dog they see in our yard, but when they get outta the yard, they're all playful and relaxed.
Tyson was broken of his fighting habit by muzzling and punishment when he displayed any sort of aggression. Peaches was broken of her fighting habit by taking her by the neck and rolling her on her belly till she was submissive. Now, the 2 dogs not only love each other, they respect me more, and they love going with other dogs that have been spayed or neutered. Tyson wasn't neutered till I got him, so he still has that dominant trait.
My view, every dog is different. Yea, some dogs are just born with that instinct to attack, but it can be broken out of them. But, when a dog attacks a human, it is NEVER the dogs fault. I've had my share of dog attacks, since in the neighborhood I grew up in had lots of strays, and not once did I ever not understand why the dog attacked me. It was either cause I was trespassing, annoying the dog, or posing a threat to the dog. I've been attacked by a dog that was in my yard from jumping over the fence and when I went out there to get him out, he went crazy on me and attacked my arm. Luckily, Peaches knew exactly what to do and she attacked him. Sometimes, having dogs that know how to attack and what to attack is a good thing. Peaches might have saved my life by getting that dog off me.
The owner is always the cause of the problem. Look at my dogs, if I didn't train them, they would be killing every dog up and down my street, but because I took my responsibility and took care of the problem, they are now very loving and people friendly. I think that every dog has that instinct to attack at one point or another. They come from wolves, so that instinct could take over at any time. If the owner didn't train the dog well, and I know the media always says, "it was a family pet" which is a lie, cause a family pet wouldn't attack the family, then the owner is stupid and deserves to be bit. Also, take into account that when a dog attacks, they always get the dog put down. Hmmm.. don't they just LOVE their dogs??
I've had one of my brothers dog attack me and we didn't get him put down cause it was MY fault. I pushed him off the trampoline and when he got back up I kicked him, so he attacked my leg. It was scary at the time, but it was no big deal later. Smokey was punished, he was locked up in a kennel every day for 2 weeks while we weren't home. After he got done with his punishment, he loved me and would always lick where he bit me, like he was saying he was sorry.
Anyways, people who just kill their animals because of the problem need to get rid of their children. If you can take care of a childs problem, then you can take care of a dogs problems.
There's also that factor that some people just flat out don't know how to raise dogs. There's also people who train their dogs to attack people when they have kids. That doesn't make any sense to me. Train the family pet to attack a burglar when the kids are gonna be running in and out of the house. Duh, that's asking for a problem.
But yea, that's all the ranting I'm going to do for now. :)