I'm really open with absolutely everything - so people are frequently horrified about what I tell my son (or how I say it). Like explaining death to him. "That rabbit? It's dead. It ran in front of a car and was run over by it and now it's dead." "This is poison. If you eat it you will die." He is now afraid of the cupboard under our sink, where I keep our household cleaners. It's still locked but he doesn't go near it because he knows that there are things in there that will kill him.Cool. It's the people that want to shelter their children from anything untoward, unpleasant or even reality that tend to be a problem.
A lot of people gave me grief about teaching my son -anything- to do with death. I think it's rather important that he understands his mortality before he finds it compromised. We're very matter-of-fact with him.