Thumb sucking is a common habit developed by children and begins as early as in utero. However, it becomes problematic when a child continues to suck their thumb past the age of 4 years, when their secondary dentition is developing and preparing to erupt. Prolonged thumb sucking into adolescence can have deleterious effects on dental and skeletal structures based on the duration and how frequent the child engages in this nonnutritive sucking habit. Thumb sucking can lead to various types of effects such as increased overjet, anterior open bite, posterior cross bite, maxillary arch constriction, high palatal vault, and Class II malocclusion. This paper presents a case study, which focuses on chronic thumb sucking in a family, the dental and skeletal changes that the family members experienced, and whether or not this prolonged behavior can be genetically influenced. Based on this case study and the field of behavioral genetics it is possible that there can be a genetic component to the duration of thumb sucking into adolescence.