Genetics, Trauma. Deviated septum is either caused by some form of nose trauma at any point in life, but it can also be caused by you inherited genes. Good luck from nyc.
Injury, development. It can be due to an injury, or just the way the septum developed. Main symptom would be nasal obstruction in one or both nostrils. The problem can be confined ot the septum (nose is straight) or the outside of the nose (nose is crooked). For advice see ENT doc or facial plastic surgeon.
Deviated septum. A deviated septum is a common issue. It can be caused by trauma, position in utero and even during the birth process. If there are symptoms like nasal obstruction, snoring or recurrent sinusitis, have your nose evaluated by a board certified otolaryngologist.