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.