From Smithsonian.com: It's not your imagination: You may be among the estimated 20 percent of people who are more likely to get bitten by mosquitoes. The problem is, there's not much you can do to lower your odds of being attacked other than using a good repellent, scientists say. Genetic factors and pregnancy are among the leading theories explaining what attracts mosquitoes to one person over another.
Some researchers have started looking at the reasons why a minority of people seem to rarely attract mosquitoes in the hopes of creating the next generation of insect repellants. Using chromatography to isolate the particular chemicals these people emit, scientists at the UK’s Rothamsted Research lab have found that these natural repellers tend to excrete a handful of substances that mosquitoes don’t seem to find appealing. Eventually, incorporating these molecules into advanced bug spray could make it possible for even a Type O, exercising, pregnant woman in a black shirt to ward off mosquitoes for good.