This is extremely common, especially in Caucasians.  Other causes are developmental, which may be associated with a high-arched palate.  Deviations can run in the family with parents and or siblings having the same problem.  Trauma is often associated with a deviated nasal septum and this trauma may also have other bony injuries to the nasal bones or the mid-face.  There are four types of deviated nasal septum.  The first one is a simple anterior dislocation.  The septum may have a C-shape or an S-shape deviation or may simply have a spur to one side.  The results of a deviated nasal septum include nasal blockage which may be on both sides due to compensatory turbinate enlargement.  Post nasal drip, nose bleeds, sinusitis, poor smell, middle ear disease, headaches, and external nasal cosmetic deformities may also arise. 

What is a Deviated Nasal Septum (DNS)?: