Causes of Scoliosis: Scoliosis may be due to many reasons but the main reasons are diseases in the joints of bones, under-developed legs, infantile paralysis, rickets, carrying heavy loads on one shoulder, unhealthy conditions, such as inadequate lighting arrangement, uncomfortable desks, partial deafness and wrong standing posture. It may be caused by congenital or acquired abnormalities of vertebrae, muscles or nerves.