At your next barbecue, your friend may be slapping mosquitoes left and right, while they just aren't that into you. Don't be insulted: It may have to do with the chemicals in your skin, Jill Richardson explains at Salon. There are 346 chemicals involved in the scent of human hands, a study found in 2000, and 277 of them can attract the annoying critters. A key one seems to be l-lactic acid, which, when added to the scent of a less-targeted person, can make certain mosquitoes go after them. It's also been suggested that some people are lucky enough to carry chemicals that actually get in the way when mosquitoes are looking for lunch.
And when it comes to malarial mosquitoes—not a big problem in the US—the bacteria in foot odor is tempting. They'll even go after limburger cheese, which smells like feet, Richardson notes. As for how to deal with them, there's controversy over the use of bug repellent DEET, which Salon calls mildly neurotoxic. But Mother Jones notes that the cause of supposedly DEET-linked seizures in children in the 1980s remains unclear, and newer studies have shown little in the way of health risks from small amounts of the stuff. Still, if you want to avoid it, a recent study suggested lemon eucalyptus oil could do the trick against mosquitoes.