The development of the human being progresses according to a symmetrical plan; under normal conditions, the relative growth of the various parts of the body proceeds equally and proportionately. There are many examples in nature of forces acting on a part of the organism to diminish the resistance or to alter the vitality of that part. In osteoporosis of the skull, the force of constant pressure exerts itself on the skull and alters its symmetry.
Asymmetry of the head and face of minor degree is common, but in the pronounced degrees it is uncommon. This condition is more easily recognized in infants, because of the sparseness of the hair on the head. When mentioned in textbooks, it is generally dismissed in a few words. In this category, we shall not consider asymmetry that results from molding of the head during labor, for these deformities usually disappear after a few days
GREENE D. ASYMMETRY OF THE HEAD AND FACE IN INFANTS AND IN CHILDREN. Am J Dis Child. 1931;41(6):1317-1326. doi:10.1001/archpedi.1931.01940120054006