Well I will get flack on this, but bad parenting is just that. I taught mine at a very young age not to touch a hot stove. No I did not put their hand on a hot stove, we taught them what hot is. Firearms are the same way, do not touch. Visiting kids parents were giving a talk about what their kids knew. We knew the parents well and their kids to.
I dont care how well you keep stuff up and away and locked up, a kid will find a way to get at it. When someone new to us comes over we pull them to the side and tell the parents that their child is to be kept a very close eye on. We have a pool, way more danger then a firearm. Being a good parent is very tuff, not something to be made lite of. Some parents think it is OK to let a kid run wild, not in my house, all kids become mine in my house. I am not saying I just leave a firearm laying around. They are accessible to a point and they are loaded.