Why does it happen like this with me?

I have always noticed that whenever I got drenched in rain in my city Bangalore, I almost always got cold and cough and sometimes even fever too but many times in hometown Siliguri and probably in Falakata too I played in rain during my childhood but never got cold. Why does it happen so? I asked my grandpa in Siliguri about it and he said "Thats because Siliguri is your birthplace so you can't get cold or cough in your birthplace".