Ever since I can remember my youngest brother has had a twitch of some sort. First off he was born three months early weighing one pound four ounces and twelve inches long. He has severe asthma and allergies. He s strong but no body fat what so ever. Anyway ever since I can remember he has had a twitch. First it started with him literally kicking himself in the butt, now he really only did that when he was nervous or anxious, everyone got on his case about him doing that because it annoyed them, he gradually quit doing it and we moved on. For the last 3 years he has now developed several twitches that he doesn t realize/comprehend that he is doing it. While watching tv, riding in a vehicle, or simply just having a conversation with some one, he has started twitching his head from side to side, up and down, twitches his eyebrows uncontrollably, or snaps his fingers for no reason. I have asked him repeatedly why he does these things and he says he doesn t realize he s doing them. Now I have seen him do it more intensely when he is anxious or nervous, but I am truly worried for his well being. I ve read about torrets and I ve read about Huntingtons and some of these symptoms are exactly what my brother has. Neither side of our family has either of these diseases. So my question I guess is can a person get these diseases with out it being in your gene pool. I m not talking about air borne stuff I m not an idiot, I m more interested in if it s linked to a genetic mutation, or if it s been in our gene pool and has just not surfaced until my brother came along being a premature baby, also he was a twin the smaller of the twins, the other twin has none of these issues. If you could shed some light on this subject for me that would be great thank you.