You suffer from the same syndrome with which I am afflicted, my friend.
Even though I know that once seen, there are things that cannot be unseen, I still click. In fact, if I'm ever unfortunate enough to be placed in a room with a big red button and a sign which says, "do not press the big red button" I suspect that I could probably hold out for no longer than ten minutes, tops.
Oh yes. The same goes for bare wires sticking out of a wall. I HAVE TO KNOW if they're live or not by touching them.
Since I believe that you're 40ish Roger, does that mean that:-
a) you've been lucky ?
b) you haven't come across many bare wires ?
Sorry Kirst- can't come up with any knob advice or gags.