Allergies, whether spring sneezes due to pollen or trouble breathing triggered by a certain food, are caused by a combination of someone's genes and the environment they live in.

The more things two people share, the higher their chances of being allergic to the same things. Twins are more likely to share allergies because of everything they have in common, but the story doesn ...

An allergic reaction happens when your immune system overreacts to something that should be harmless. Whether that happens ...