I'm a major animal lover and dog person and I consider myself someone who understands dog psychology pretty well. Still, I stay out of these threads because they get so contentious between pit bull owners and others. I just make some popcorn and watch everyone try to rip each other's heads off.
Javadog, it's clear that you are a dog person and someone who understands dogs and training. I'm sure that your dogs are awesome. What I'm a little surprised by is that you don't put much stock in genetics. I'm a firm believer that in dogs, (and people for that matter), personality and temperament are installed at birth and of course can be altered by environmental factors and experiences.
I think that it's about 50/50, slightly more or less. The problem w pit bulls, besides terrible owners sometimes, is that many are extremely poorly bred. Unfortunately, most dog breeding decisions are made by dogs. We all know how that goes in the alleys and parks of America. In a perfect world, dogs with personality or temperament issues would be prevented from breeding and in a perfect world, dogs would not be abused and would be trained by humans such as yourself who know dogs.
In the real world, none of that happens too often. The reason pit bulls are so dangerous is because so many are poorly bred, really defective dogs and so many owners are either ignorant or malicious in handling them. They wind up in households w children or other vulnerable people and maul them, way too often. The reason you don't read about a lot of toy poodle attacks is because, A), they rarely attack humans and B), if they did it would not cause injuries that make for an evening news story.
So even though there are plenty of nice pits that would never bite anyone, (I've known many), the reality in the real world is that some are unpredictable and attack humans or other pets without much warning and the results can be tragic. I remember years ago when a guy I know was dating one of the most beautiful actresses in Hollywood until his pit killed her small dog when they left them alone together one too many times. There had never been a hint of a problem before.
I've had dogs since I was 8, (that would be 50 years ago), all of our dogs as kids were from the shelter and were cute mutts. When I was in HS, we had a pure Old English Sheepdog who was awesome but we wound up giving her to some friends w a farm because my mom thought she needed more space, (as I remember it).
As an adult, I have had two German Shepard dogs that I each got from private breeders who had both parents. I wanted to see the parents and how they reacted to a stranger, (me), coming into their home as a friendly to see their puppies. The personality, temperament and intelligence of the dogs was very important to me. I wanted a dog that I could trust with a newborn baby or raucous 4 year old child poking them and antagonizing them without biting.
I got my wish in both cases and they were absolute Hall of Fame dogs, in a friend's words.

Neither of my dogs would bite an innocent person under any circumstances, I was 100% sure of it. One of them was ferocious w other aggressive male dogs and got in some gnarly dog fights but the other was a big baby who couldn't whip a Chihuahua.
I didn't need a tough dog to protect me, (I'm sure you don't either), I just wanted a smart, beautiful animal. I love all dogs, including pits but I have a thing for GSDs.
I may have strayed from the topic but my point is that in the real world where dogs are not always well bred and owners aren't the best, pits as well as Rottweilers and other fighting type dogs are often very dangerous and the results are gruesome.