A study of family head shape: environment alters cranial shape.

A change in the type of cranial deformities (plagiocephaly) presenting to certain clinics has occurred. The purpose of this study was to compare infant head shapes against head shapes of their biologic parents to explore the roles of heredity and environment on cranial shape. Standardized family photographs and anthropometric measurements demonstrated that 30% of the infants had cranial widths 2 standard deviations above norm, while 4.6% had widths exceeding 3 standard deviations. Despite a mean age of only 8 months, 11.6% had widths that were already greater than that of 1 parent. These results demonstrate that plagiocephaly has taken on a new configuration, presenting not only with asymmetry, but also with excessive cranial width.