Scoliosis is a problem that makes the spine curve and twist from side to side. It is most often found in girls in their early teens. But boys can have it, too. No one is sure what causes scoliosis. But we do know that scoliosis is not caused by things like carrying heavy bags or playing sports. If someone in your family (like a parent or a sibling) has scoliosis, you may be more likely to have it, too.