If you’ve ever sat in front of a plate of wings with tears streaming, sweat dripping, or snot running, you’ve probably wondered how to up your spice tolerance. While some people find themselves in a world of hurt from freshly grated black pepper on their pasta, others dive into threateningly red bowls of pozole with the enthusiasm of Guy Fieri at a cheesy-fry buffet.

More than 20 years ago, salsa crept passed ketchup in the U.S. condiment sales market, and American palates began to seek adventure in earnest. A 2013 Technomic study showed that 54% of Americans prefer spicy sauces and dips—a number that was and likely still is increasing rapidly. Unlike so many other taste preferences, though, the growth of spice brings with it a prickly issue: How much heat can your tongue handle? As supermarket snacks (Flamin’ Hot Cheetos, Sriracha Popcorn) and fast food (KFC’s Nashville Hot Chicken, McDonald’s Hot N’ Spicy McChicken, Wendy’s Ghost Pepper Fries) crank up the Scoville units, consumers are left to find their breaking point—and, if they so choose, figure out how to change it.

For those that experience an adrenaline rush from eating spicy foods, the growth of intense spice availability sounds appealing. Meanwhile, others ponder why they can’t down spice-laden soups or Scotch Bonnet pepper sauce. But what’s to blame for your spice tolerance? You can work to actively change it if you’re gearing up for a trip to Sri Lanka or Seoul, but could it be that certain people are just genetically predisposed to be immune to the capsaicin that causes spice in chile peppers? Or are those that can guzzle Sriracha and smear harissa on their hot dogs just better trained than those who cringe at curry?

With the help of flavor scientists and chile-pepper historians, we take a look at how the human body handles heat.