After an evening of playing outdoor soccer, my daughter came home a few weeks ago completely covered in mosquito bites while her friends had very few. As most of us have long suspected, scientists have now determined that about one in five people are particularly delectable for mosquitoes, getting more bites on a regular basis than everyone else.

A recent blog post on Smithsonian Magazine’s website provides some surprising factors that can make you tastier to mosquitoes. Some things you can’t control like genetics, which determine how much carbon dioxide you exhale or your blood type. Research suggests mosquitoes land nearly twice as often on those with Type O blood compared to those with Type A; Type B folks fall somewhere in the middle. The insects also prefer big exhalers of carbon dioxide.

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Pregnant women are also twice as likely to get bitten, probably because they exhale more carbon dioxide and have slightly warmer body temperatures — which also attracts the insects.

These are the same reasons mosquitoes tend to bite those who exercise outdoors. Sweat also contains lactic acid, uric acid, ammonia and other substances that mosquitoes are drawn to by smell.

If you’re having an evening barbecue, you may want to skip the beer. One study suggests that consuming a single bottle of beer is akin to wearing a “bite me” sign for insects to read, though scientists haven’t determined a reason why.

Wearing certain colors—such as black, navy, or red—may also draw mosquitoes to your skin. Update: A reader who read this post e-mailed me to explain why. Dark colors radiate heat more effectively, and mosquitoes are attracted to this body heat.

Of course, the best thing you can do to avoid mosquitoes — if you’ve been a tasty meal for them before — is to cover up with long pants and long sleeves in the evening or to spray on insect repellent. (Check out the video above for which ones work best.) You can also try exercising outdoors in the early morning when mosquito activity tends to be low.

If you’re having on outdoor party or barbecue on your deck, try setting up a fan to create a breeze. Mosquitoes are weak fliers and don’t like flying in winds, so this will keep them away, according to this New York Times article. The breeze also disperses human emissions like carbon dioxide so the biters don’t know where to track down the source of their next meal.