The fact that you breathe through your mouth could have multiple causes, but it is hard to say if there is something wrong with you without knowing more about you. That is why it is important to discuss this concern with your doctor
. There are some cases where an obstruction at the back of the nose makes breathing through the nose impossible. This could be concerning, especially if it was a new and progressive problem that could indicate a potential serious problem. It could also be relevant if it is contributing to other problems such as obstructive sleep apnea
. For most people, however, it could just be a minor inconvenience or annoyance (or not even bother them, as in your case!). Any obstruction, at the front or back of your nose could be causing this problem, or it could be a learned behavior from when you were younger and did have an obstruction, such as large adenoids. In and of itself, open mouth breathing may not be a serious problem, but it is impossible to tell for sure without in person evaluation. If it is something new or you have any other problems, this could be more serious. Regardless, please discuss this with your doctor to determine if all is well.