The main cause of cleft lip and palate is genetic factors, in addition, it is also related to environmental factors. 1. Cleft lip and palate is a congenital developmental malformation of the oral and maxillofacial region, which can be manifested as a separate cleft lip or palate, or as a cleft lip combined with a cleft palate. 2. Cleft lip and palate is determined by both genetic and environmental factors. Genetic factors are the main cause, which can be familial or caused by gene mutation, abnormal chromosome duplication or deletion. If someone in the family has had a cleft lip, the chances of the infant developing a cleft lip increase. It is also associated with environmental factors, such as the mother’s physical condition in the early stages of pregnancy, diet, certain medications taken, and exposure to viruses and chemicals.