Is twitching a sign of some kind of disorder?

I'm 12 years old and sometimes, out of nowhere, my eyebrow, arm, leg, etc twitches and spasms. It's not really noticible, but I can feel it but can't control it. If my friends look really close, they notice it but at a respectable distance, they don't see it. I've been having them for a while and I don't know why. I'm healthy, a little over-weight, but I don't have a disease or disorder. A lot of stuff runs in my family life diabetes, ADD, ADHD, dyslexia, cancer, heart problems, lung problems, etc, though I'm not sure if that matters. I do have mild allergies during spring and I usually get severe cases of bronchitis during the winter, but again I don't know if that matters. I don't do drugs or take medication but I probably do have second-hand smoke. Can someone please help me, I'm really worried. Hopefully I'm just a drama queen!