When you were growing up, you [as was I] were probably hit with more than a few "mom rules." You know, bits of wisdom that were passed down from generation to generation. The only problem was that a lot of those rules turned out to be terribly wrong.

Ken Jennings [yes, the one who took home $2.5 million from his incredible run on Jeopardy! ] decided to look into mom rules for his new book Because I Said So!  Here are a few rules, and whether or not they hold water:

"When you open the oven, all the heat goes out" - Not really, says Jennings. He found out that as much as 25 % of the heat leaves your oven through an open door. But it's replaced in seconds by heat radiating from the oven walls.

"Coffee stunts your growth!" - Nope. This one probably started when caffeine was lumped in with tobacco. Smoking will stunt a child's growth. But coffee is used in some parts of the world to help treat premature babies.

"Let cuts air out so they heal!" - This one has been known to be wrong in the medical community for a half-century. The trick to get wounds to heal is keeping them moist, not letting them dry. Try a little petroleum jelly, then cover the cut with a bandage. Day and night.

You can find some more discredited "mom rules" here, and more still in Jenning's new book.