How many of you “learned” growing up that swallowed gum takes 7 years to clear you system or you can derail a train by leaving a penny on the track or public pools have a urine-detecting chemical added to the water? What others were you told? I’m not asking about the ones that are clearly ridiculous (if you make that silly face it’ll freeze that way or swallowing watermelon seeds will cause watermelons to grow in your stomach.) I’m asking about the ones that have the ring of truth that many parents might actually still believe themselves.
The old adage about not swimming for an hour after you eat comes to mind.
Bread crusts have more nutrients in them, so it’s not good to leave the crusts on your plate. I think I was in college before I really thought about that and went “wait a minute…” :smack:
Lightening is attracted to noise, you have to be quiet during a thunderstorm.
Lightning never strikes twice in the same place.
Mothers have eyes in the backs of their heads.
I told my kids that ‘shut up’ was a swear word.
I never heard any of that from my parents. That was stuff learned at school, from the bigger kids.
I’ve never heard that one. Is it regional?
Honest to god, a kid that tells someone else to “shut up” comes across as a lot more rude and mannerless than a kid who lets slip a “damn” when they drop their ice cream cone.
ETA: Erma Bombeck wrote once that she taught her kids that steak makes children sick.
Yes, Victor Charlie, there is a Santa Claus.
And the old American patriotic standard stories about Washington and the cherry tree, and Lincoln trudging miles through the snow to return a borrowed nickel. (Actually, I suppose a nickel would have been a significant sum in those days.)
It was generally believed in the 1400’s that the world was flat. Columbus was a really innovative thinker (and maybe even a heretic) to believe that the world is round, and a reckless foolhardy adventurer for sailing west, quite probably only to fall of the edge of the Earth, to prove it. Likewise, Good Queen Iz was a fool for financing such a mad venture.
Cecil Adams exists.
See also Lies My Teacher Told Me and Lies Across America by James W. Loewen.
The car couldn’t start if the seat belts aren’t buckled.
Well, technically not a lie, since I wouldnt start it…
He was reckless and foolish, just for different reasons. His ideas about the world were totally wrong.
The only falsehood I remember being told is the one about not swimming for an hour after a meal. But it wasn’t a lie; she believed it and so did I. Oh, here is one she told me when I was in college, if you can believe it (she apparently did): sleep before midnight is twice as beneficial as sleep after. Also that to lose weight you should drink less water. (“Are you trying to claim that water has no weight?” I was speechless. Of course, I should have said that you are not trying to lose weight; you are trying to lose fat. But I didn’t think fast enough.)
Oh I told my little girl about the pool urine thing just last month. It always kept me from letting loose in the pool when I was a child.
My mother heard it from her grandmother, who had a whole houseful of kids.
She figures my grandmother told the kids that to save her sanity when they were all stuck in the house together during the storm.
My mother passed it on to us and I still feel like I have to be quiet during storms,
My next door neighbor told me that when you fall asleep, your heart stops beating. I used to lie in bed with my hand over my heart to see if it was true. She also told me if you touch your window screen when lightning flashes, you’ll be electrocuted. She was pretty mean to naive little me.
My grandmother told my mom that bread crusts gave you curly hair. 
The tofu-version is even better.
Ken Jennings collected a book of these, Because I Said So!: The Truth Behind the Myths, Tales, and Warnings Every Generation Passes Down to Its Kids.
Q: Where do babies come from?
A: The hospital.