Deviated nasal septum is not a disease. The nasal septum is only a partition in the nose, it is almost never straight. Unnoticed injury to the nose in early childhood when learning to maintain balance is the most common cause of this injury. Air can take a curved passage with ease, the cause of nose block therefore lies in dysfunction of structures within the nose other than the septum; nasal turbinates being the most common. If surgery has been suggested for this, it's time u take a second opinion.