I always always always have to knock on wood, and I have to knock exactly 3 times (because that's a good number.) This probably comes from the time I was driving home and thought to myself, "Gee, I've never gotten a speeding ticket!" And then, 5 minutes later, guess what happens! So now I have to knock on wood every time I think something like that or I freak out :)
As far as the superstitious thing.. I do not have a superstitious bone in my body. The closest I might get is to have a pork and saurkraut meal on New Years Day, but I only do that every otherNew Years Day or so, and am really only doing it for tradition.. like turkey on Thanksgiving day.
My maternal Grandmother was a midwife in the early 1900's, when I graduated Nursing School my mother passed down her medical journals on midwifery, I loved reading the medical advice which was nothing more than superstition, but at that time was on the edge knowledge.