Have you ever made a point of not warning children about something dangerous, in case it tempts them to try it, making it forbidden fruit, or to avoid frightening them? It does of course depend on your children’s personality, and if they are likely to take risks.
My dad recently told me that when I was eight or nine, a holiday cottage where we stayed had deadly nightshade berries growing in the garden, and he decided not to warn me about them, in case it tempted me to eat them. (He did warn me about plenty of other mortal dangers, though.)