Actually, vicarious learning of fear through your parents is another aspect that Idiot Brain addressed, and he provided essentially the same explanation. If adults we trust are afraid of something, then surely we should be as well. And yes, it certainly makes sense from an evolutionary standpoint. We benefit from others' mistakes, so to speak (i.e. One wouldn't get killed by a large predator because one's parents witnessed such a death).
I guess my DSs won't be afraid of water snakes - I once caught one bare-handed just so that I could show it to them up close. I was so excited to hold it for a moment, even though it bit me. I was even happy to show them the fang marks!
Ok, back to my day job!
