I will admit that I have readily available firearms around the house, but luckily my kids are 14 and over and have been around firearms all their lives. When my son was young and curious I adopted a "never say no" policy when he asked to see them. As a result, he knew that he could see and shoot them anytime, all he had to do was ask and I would not say no. I would happily take him out and supervise his activity. Because he knew he could see them anytime (and I taught him safe handling and clearing) he never attempted to "sneak" and mess with my guns. There was no need because he was never denied supervised access.
The long and short is that education is imperative and execution is the best educator.