Bone responds physiologically to its mechanical environment. There is a specific response of growing bone, especially of a bone's growth plate that is different from that of mature bone. The growing skeleton can develop deformities in response to abnormal loading environment. Scoliosis of the spine and 'bow- leg' deformities of children are thought to progress during growth because angular deformity produces asymmetrical loading, which produces asymmetrical growth, etc. in a 'vicious cycle'. However this is only qualitative hypothesis, requiring quantitative scientific testing. Our work addresses two difficult links in this supposed chain: 1: How asymmetrical is the spinal loading in a scoliosis? 2: How does bony growth respond to the abnormal loading? Both questions cannot be answered directly in growing children - to answer these questions we use analytical modeling (of spinal loading) and animal models (of mechanically altered growth). So is the cycle vicious or benign? The answer appears to be 'vicious', and the details will be presented.