Contribution of genes and environment to the etiology of malocclusion has been a matter of controversy throughout the twentieth century. Genetic mechanisms are clearly predominant during embryonic craniofacial morphogenesis, but environment is also thought to influence dentofacial morphology postnatally, particularly during facial growth. Orthodontic and orthopaedic techniques are used in the treatment of malocclusion and other dentofaical deformities, but with limited effectiveness. The key to the determination of the aetiology of malocclusion, and its treatability lies in the ability to...