Did you guys get an allergy later in your life ?
example
I mean didn't have allergy for prawns early, but all of a sudden you got and now having it.
Of course yes.. Adult allergy is quite common. Genetics plays its own role and immune system changes. First you develop sensitization, where for a harmless substance, body mistakenly starts making allergic IgE antibodies. These antibodies don’t do anything until you are exposed to the substance, or allergen, again.
Then the fun begins, the allergen binds to the antibodies resulting in various reactions.
The exact reasons are unknown. Allergies run in the family. The ability to develop allergies is inherited. Sometimes skips a generation. My father was allergic to Pineapple, he could never eat it without a reaction but I am not. My son started it around 4 years, his face becomes rosy and bumps appear on his body. But I didn't stop him from eating pineapple. Now he eats half a pineapple without any reaction. The allergy disappeared. He turns 22 next week, but you never know it could trigger later in his life.
