What is a harelip? A harelip is a cleft defect in the space between the upper and lower lips and the mouth, which is common in newborns. Generally speaking, during the development of the fetus, the facial tissues should fuse between the mother\’s palatine processes to form an oral cavity. However, sometimes this process goes wrong, causing a crack to form between the upper lip and the mouth, a condition known as harelips. Hare lip is a congenital disability that often requires surgical treatment, affecting the patient\’s appearance and physical and mental health. Is harelips hereditary? The genetic factors of harelips are complicated and not