Influence of genetic and environmental factors on transverse growth.

This study investigates the genetic and environmental influences on transverse craniofacial growth in monozygotic (MZ) and dizygotic (DZ) twins of European descent at ages 9, 12, and 15 years, using postero-anterior (PA) cephalometric radiographs. Results indicate that most transverse dimensions, including maxillary, mandibular, nasal, facial, and intercanine widths, show significant genetic influence at earlier ages, with additive and dominant genetic factors accounting for a large portion of variance. However, environmental factors increasingly affect certain measurements, notably intercanine width at age 15, where environmental influence reached 84%. The findings suggest that genetic factors predominantly govern skeletal transverse growth, while environmental factors have a greater impact on dental transverse dimensions during adolescence. Limitations include the sample's restriction to individuals of European descent and the absence of genetic sequencing or detailed medical histories.