The Heritability of Facial Morphogenic Traits among the Ijaw People of Yenagoa: Dimple, Philtrum, Gap Teeth and Mentolabial Sulcus
Edafe Gift Daniel
*
Department of Human Anatomy, Faculty of Basic Medical Sciences, College of Health Sciences, Delta State University, Abraka, Delta State, Nigeria.
Odokuma Emmanuel Igho
Department of Human Anatomy, Faculty of Basic Medical Sciences, College of Health Sciences, Delta State University, Abraka, Delta State, Nigeria.
Efe Jennifer Jaiyeoba
Department of Human Anatomy, Faculty of Basic Medical Sciences, College of Health Sciences, Delta State University, Abraka, Delta State, Nigeria.
*Author to whom correspondence should be addressed.
Abstract
Background: Facial morphogenetic traits such as dimples, philtrum depth, midline diastema (gap teeth), and mentolabial sulcus morphology are genetically influenced anatomical features that contribute to craniofacial variability and are useful in anthropological identification and inheritance studies. However, there is limited information on their heritability patterns among indigenous Nigerian populations.
Aim: This study investigated the heritability patterns of selected facial morphogenetic traits among the Ijaw people of Yenagoa, Bayelsa State, Nigeria.
Materials and Methods: A descriptive cross-sectional observational study was conducted among 150 participants drawn from Ijaw families using a simple random sampling technique. Data on the presence and distribution of dimples, philtrum depth, gap teeth, and mentolabial sulcus morphology were collected from parents and their first and second children through direct visual assessment under standard conditions. Statistical analysis was performed using SPSS version 25 with chi-square tests at a 95% confidence interval to determine inheritance associations between parents and offspring.
Results: The findings showed generally low prevalence of gap teeth and facial dimples among parents and their offspring. Average mentolabial sulcus depth was the most frequently observed pattern across families, while shallow philtrum depth predominated among both parents and children. No statistically significant association was observed in the inheritance of gap teeth and mentolabial sulcus between parents and offspring (p > 0.05). However, significant associations were identified in selected patterns of philtrum inheritance among second children and in the absence of dimples among both first and second children (p < 0.05), suggesting partial hereditary influence.
Conclusion: Facial morphogenetic traits among the Ijaw population demonstrate variable inheritance patterns, with some traits showing significant familial association. These findings provide important baseline anthropogenetic data useful for craniofacial research, forensic anthropology, and population-based genetic studies in Nigerian ethnic groups.
Keywords: Heritability, dimples, philtrum depth, gap teeth, mentolabial sulcus