Scoliosis is primarily caused by an abnormal sideways curvature of the spine. The most common form is idiopathic scoliosis, which means its exact cause is unknown but is believed to involve genetic and environmental factors. It often develops during growth spurts in adolescence, particularly around puberty. Other causes include:

• Congenital scoliosis caused by spinal bone malformations present at birth.
• Neuromuscular conditions like cerebral palsy or muscular dystrophy.
• Degenerative scoliosis in adults due to aging, spinal disc degeneration, or bone weakening.
• Injuries, infections, or tumors affecting the spine.

Genetics plays a role in about 30-65% of cases, but no single gene is identified. Rapid spinal growth during puberty can trigger or worsen scoliosis. Risk factors include being female (with higher curve progression risk), older age, and certain spinal conditions. Some scoliosis cases are due to muscle imbalances or leg length differences but these often resolve when the underlying cause is treated. Most scoliosis cases, especially in adolescents, do not have a single clear cause and are considered multifactorial with a combination of genetic and environmental influences.