Myth: Opossums sleep hanging by their tails. You've probably seen cartoons—maybe even photos—of opossums lounging upside-down from their tails. While opossum tails are strong enough to grasp branches and even hold the animals' weight for a short period, adults are too heavy for their tails to support them for long, so they can't stay like that while sleeping. Don't play possum, have you ever heard this myth before?

Myth: Lightning never strikes the same place twice. Anyone familiar with lightning rods could probably already tell you there's nothing stopping lightning from hitting the same spot twice. The Empire State Building, for example, once endured eight strikes in 24 minutes during a storm. Even without a lightning rod, there's nothing keeping lightning away from the spot that just got hit. In fact, the features that made the spot likely to get hit once—height, presence of standing water, or terrain shape, for example—would be just as attractive to a second bolt, according to the National Severe Storms Laboratory. Were you aware that lightning can strike the same place more than once?

Myth: Common belief in the Middle Ages was that the Earth was flat, but it's really a perfect sphere. Surprise! Both parts of this myth are false. Scholars have known the Earth is round for thousands of years. The Greek philosopher Pythagoras first suggested the idea around 500 B.C., though his thought process had to do with the fact that he thought spheres were the most perfect shape. Still, Aristotle actually found physical evidence backing up his predecessor's theory. By the time the first century A.D. rolled around, any educated Greek or Roman believed in a round planet. When Christopher Columbus took on his voyage, the fear was that the oceans would be too big, not that he'd fall off the face of the Earth. In perhaps the biggest twist, though, Earth isn't a perfect sphere; the North and South Poles are flattened slightly. Are you a flat earther?

Myth: Genes determine race. You might think people who look superficially different would have big differences in their genes, but that's not the case. According to the National Human Genome Research Institute, humans share 99.9 percent of their genes with each other. Even that 0.1 percent doesn't have any racial markers. In fact, a groundbreaking 2002 study revealed there is more genetic diversity between people of African descent than between Africans and Eurasians. You can use your genes to trace your ancestors' geography, but that doesn't directly tie into race. Case in point: Sickle cell anemia isn't a general "African" disease, as it's normally described; it's more common in West Africans, but it's also widespread among Mediterranean, Arabian, and Indian populations. Did you think your race was determined by your genetic makeup?