Under normal circumstances the spine is straight; however, if you or your child has scoliosis the spine will get curved in the upper or middle section. The size of the curve differs. Smaller curves are more common than larger ones. The disease affects girls more severely than boys. It most commonly starts after the age of ten but can also develop in much younger children and even babies.Although the exact cause is unknown it is not believed to be caused by posture or physical activity.