Scoliosis is a condition of side-to-side spinal curves that measure greater than 10º. On an x-ray, the spine of a person with scoliosis looks more like an "S" or a "C" than a straight line. These curves may cause your shoulders or hips to be uneven, depending on where your curves are located in your spine.
Idiopathic scoliosis is by far the most common kind of scoliosis. "Idiopathic" means that the cause is not known, and it develops most frequently in preteens or teen-agers. Adolescent idiopathic scoliosis (AIS) is 10 times more common in girls than boys!
Not every person with scoliosis needs to be treated. Your doctor will decide whether your curve is one that may worsen and cause problems. If so, treatment may include bracing, physical therapy, or—in the most severe cases—surgery. If the angle of your spine's curvature measures less than 25º, your doctor will probably decide to "watch" it by x-raying your spine every 4 to 6 months. If your curve reaches 25º, your doctor will probably discuss bracing.
Because the majority of scoliosis diagnoses are idiopathic, much of the time the cause of the scoliosis is not known. Many of the doctors and researchers in the Scoliosis Research Society are working to identify the genes that cause AIS.
Just as you can't prevent scoliosis, you also can't cause it. Poor posture does not cause scoliosis.