Should Children be told about STD's, , death, murder, etc. as early as possible?

i think that kid should know what can happen to them if they are old enough to ask but with that you should also tell them how to protect them self because most kids already know about what can happen but what they don't know is that they can fix it~ fairytale don't teach children that dragons are real they already know they are real what it teaches them is that you can kill them