genetics + environment = end product.
The genetic base for Zeeva's temperament was already there when you got her - she would not be miraculously stable if she were raised with a different handler. She is who she is, and her environment shaped her.
And if you start thinking like that, you'll also have to consider the fact that perhaps you HELPED Zeeva greatly into becoming as capable as she is today - in a more passive or neglectful home, she could have become a real problem.
If we take my current pup as an example: she is who she is, and nothing I do will change her base temperament. However, depending on how I raise, socialize, train, and develop her, she will grow and stabilize within the confines of what her genetics allow her. I can see this in training clubs - pups can exceed or fall short of their genetic expectations because of their environment and handler. However in the end, they can only have leeway within the range that their genetic capability allows.