Between old wives tales, marketing scams, media messages, and good old fashioned rumors, there are plenty of commonly held beliefs that are just not true. Will a detox diet cleanse your system? No. That idea that men and women have different brains? False. Do you really need 10,000 steps a day? Not really. (Though, it couldn't hurt.) But figuring out what to believe can be a difficult, and seemingly endless, task. That's why we've done the work for you. Here's the truth behind some concepts you've probably heard — and believed — for a long time. And if someone ever asks you to pee on their jellyfish sting, you can let them know that's not a thing. You're welcome.