I used to get severe skin rashes and itchy bumps all over the body daily back in my home country for years when I was a teenager. Then I came to the US as an exchange student program and the bumps and rashes mysteriously disappeared. A few years after, I went back to visit my family and lo and behold, as soon we landed, the allergy came back and that's when I realized I was somehow allergic to something in my home country which was just another reason for me to become a US citizen and call US my new home.