There are many ideas we grow up believing without a second thought. They come from classrooms, parents, and conversations, and we hear them so often that they feel unquestionable. Over time, these assumptions settle in as truth, even when they are based on misunderstandings or outdated information.
Not everything we believe is accurate. Some of the most familiar beliefs are surprisingly wrong, yet they continue to circulate as common knowledge. Stick around and see if there’s any false information you’ve been spreading without knowing. Let’s dive into 15 false facts people think are real.
1. Humans only use 15% of their brains
This idea is completely false. Brain imaging shows that we use virtually all parts of our brain over the course of a day, even during simple tasks or sleep. The myth likely began in the early 1900s when psychologists noted that much of the brain was unexplored. Over time, that uncertainty turned into an exaggerated claim that stuck in pop culture.
2. Cracking your knuckles causes arthritis
There is no scientific evidence linking knuckle cracking to arthritis. The sound comes from gas bubbles popping in the joint fluid, not from bones grinding together. This rumor likely began as a way to discourage an annoying habit. Parents and teachers passed it along, and it ended up sticking.
3. Sugar makes kids hyper
Research has shown no direct link between sugar consumption and hyperactivity in children. The behavior people notice is often due to exciting environments like parties, and not the food. It can also be the caffeine content in sodas causing the hyperactivity, rather than the sugar. The idea gained traction in the 1970s during increased concern over children’s diets.
4. You swallow multiple spiders a year in your sleep
There is actually no evidence supporting this claim. Spiders generally avoid humans and are unlikely to crawl into a mouth. The rumor originated from an experiment meant to show how easily misinformation spreads online. Ironically, it worked perfectly.
5. Lightning never strikes the same place twice
Lightning actually can and often does strike the same place multiple times. Tall structures like skyscrapers and radio towers are hit repeatedly. This saying began as a figure of speech meant to describe rare events, and over time, it was taken literally.
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6. You should wait an hour after eating to swim
There is no rule requiring you to wait after swimming, and it’s because it isn’t considered dangerous. Mild cramping has occurred after eating, but it’s rarely dangerous. The warning likely came from parents trying to keep kids safe and easier to supervise.
7. Bulls hate the color red
Bulls are colorblind to red and react to movement, not color. In bullfighting, it is the motion of the cape that provokes them, and the red fabric is used for tradition and visual effect. The myth formed from a misunderstanding of what triggers the animal.
8. Eating carrots dramatically improves eyesight
Carrots are healthy and contain vitamin A, but they don’t give you super vision. This myth became popular during World War 2, as British officials spread it to hide the use of radar technology, attributing RAF pilots’ success to carrots while encouraging citizens to grow more food during rationing. The story stuck long after the war ended.
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9. Shaving makes hair grow back thicker
Shaving doesn’t change the thickness or growth rate of hair. The blunt ends of shaved hair can feel more coarse, creating the illusion of thicker growth. This belief spread because the change is noticeable at first, but science shows hair growth isn’t truly affected.
10. Microwaves destroy the nutrients in food
Microwaves don’t destroy nutrients any more than other cooking methods. In some cases, they preserve nutrients better because cooking times are shorter. Fear of New technology fueled this misconception, and the lack of understanding of how microwaves work added to it.
11. Alcohol kills brain cells
Responsible alcohol consumption doesn’t kill brain cells directly. Excessive drinking can damage brain function, but not in the way that is often described. This myth was popularized in school programs meant to discourage drinking.
12. You lose most of your body heat through your head
Heat loss depends on what parts of the body are exposed. The head loses heat at a similar rate to other uncovered areas. This idea came from military studies where soldiers weren’t wearing hats. The results were misunderstood.
13. Diamonds are rare
Diamonds aren’t as rare as people think. Their value is largely controlled by mining companies that intentionally limit supply. Marketing campaigns in the 20th century reinforced the idea of rarity, and this perception is what made diamonds symbols of luxury.
14. Waking sleepwalkers in dangerous
Waking a sleepwalker is generally safe, though it may startle them. The danger comes from sudden movements or confusion, not from the waking itself. This myth likely developed to discourage interaction during sleepwalking, and movies and folklore exaggerated the risk.
15. Mount Everest is the tallest mountain on Earth
Everest may have the highest elevation above sea level, but Mauna Kea in Hawaii is taller when measured from base to peak. The misconception comes from focusing on feet above sea level rather than actual size. Popular media rarely mention other ways to measure the “tallest mountain.”
Want to check out some fun facts that are real?
Check out 20 Eerie Yet Fun Facts That Most People Don’t Know, or take a look at 20 Real-World Facts That Sound Like Glitches In The Matrix. Finally, if you want to see fun facts about sleep, check out 20 Fun Facts About Sleep.
