You come in from a summer hike covered with itchy red mosquito bites, only to have your friends innocently proclaim that they don’t have any. Or you wake up from a night of camping to find your ankles and wrists aflame with bites, while your tentmates are unscathed.

You’re not alone. An estimated 20 percent of people, it turns out, are especially delicious for mosquitoes, and get bit more often on a consistent basis. And while scientists don’t yet have a cure for the ailment, other than preventing bites with insect repellent (which, we’ve recently discovered, some mosquitoes can become immune to over time), they do have a number of ideas regarding why some of us are more prone to bites than others. Here are some of the factors that could play a role: