Lessons from the Twin Study: What can we Expect from Genetics?

Our knowledge of growth and development comes from information gathered from large groups of people, which can give us general patterns of growth. We can also use implant information to learn about specific patterns of growth. However, neither of these methods help us to understand which aspects of growth are determined by genetics and which are more under environmental control. The Forsyth Twin Study, which included annual records of approximately 500 pairs of twins, their parents, and their siblings, was gathered by Dr. Coenraad Moorrees and his staff between 1959 and 1975. It is a valuable resource for investigators seeking to learn about the relative contributions of environment and genetic control. Studies done over the past several years using this sample have begun to give us such information regarding lower incisor crowding, mandibular length, nasal growth, and facial asymmetry. This presentation will describe what the Forsyth Twins have taught us about facial growth.

Learning Objectives:

• Comprehend how lower incisor crowding and mandibular length are determined by genetics versus the environment.
• Analyze whether children tend to resemble one parent more than another.
• Identify whether mirror asymmetry occurs in the facial growth of twins.