The sad reality is that much of what we "know" is simply wrong. Hardly a day goes by without someone, usually me, espousing some half-truth we have heard most of our lives but which we have never bothered to verify. You want examples? Well, here you go:
• Cinco de Mayo is Mexican Independence Day. Wrong.
• Napoleon Bonaparte was short. Wrong.
• Searing meat seals in moisture. Wrong.
• Naked exposure to the vacuum of space means immediate death. Wrong.
• Exposure to cold or wet weather increases the likelihood of catching a cold. Wrong.
• The Bible says God made Eve from Adam's rib and it was an Apple that Eve ate that caused so much trouble. Wrong...and, wrong.
It is almost depressing how often we are just plain wrong. Much more illumination here courtesy of Wikipedia.