Predict your baby likely lip shape including full, medium, thin, bow-shaped, wide, and compact based on parental lip genetics and craniofacial inheritance models.
Fill in the fields and press Calculate. Grandparent inputs are optional but improve accuracy.
Generated at traitgen.com. Free genetics education. Not medical advice.
Fill in the form and press Calculate to see your result here.
⚠️ Educational only. Probability estimates based on genetic models, not medical advice.
The distinctive double-curved upper lip shape called the Cupid's bow is named after the Roman god of love. Its genetics are linked to TBX1 and related transcription factors. The sharpness and definition of the Cupid's bow shows strong familial clustering, making it one of the more reliably heritable lip features.
Lip shape is a highly heritable polygenic trait. Studies of twins estimate lip morphology heritability at 60 to 80 percent. Key associated genes include TBX1, PRDM16, and ESRRG, identified through large-scale genome-wide association studies of facial features.
The TBX1 gene, a transcription factor involved in craniofacial development, is associated with mouth width and lip proportions. Variants in TBX1 affect the lateral growth of the lip region during fetal facial development, influencing whether a person develops a wider or more compact mouth relative to face width.
Lip fullness is largely determined by the volume and distribution of fat pads and the thickness of the orbicularis oris muscle around the mouth. Both are heritable. Genes regulating adipocyte development and facial muscle thickness contribute to the spectrum from thin to full lips, independent of overall facial structure.
The distinctive double-curved upper lip profile called a Cupid's bow is shaped by the philtrum and vermilion border development. The depth and sharpness of this feature is heritable, controlled partly by the same genes that regulate lip ridge formation. It is more prominent in some populations due to ancestral genetic clustering.
Lip fullness shows significant sexual dimorphism. Oestrogen promotes fuller lips and a more defined Cupid's bow, while testosterone tends to produce thinner, straighter lips. This means the same underlying lip-shape genetics may be expressed differently in male and female children from the same parents, making lip shape prediction less precise than for other traits.
Lip fullness is substantially heritable. However, lip volume decreases with age due to gradual loss of collagen and fat in the perioral region. Children often have proportionally fuller lips than their adult counterparts will, and lips tend to thin slightly from the mid-twenties onward. The underlying shape and width ratio, however, remains relatively stable throughout life and reflects genetics more reliably than volume alone.
Yes, though it is less likely. Lip fullness is polygenic, so if both parents carry some alleles for fuller lip volume without fully expressing them, a child could inherit a combination that produces fuller lips. This is more likely when grandparents on either side have noticeably fuller lips than the parents themselves.
Medium-thickness lips with a moderate Cupid's bow are the most common globally. Full lips are particularly common in people with African ancestry, while thinner lips are more common in people with Northern and Eastern European ancestry. Wide mouths relative to face width are more common in East Asian populations. These are statistical tendencies reflecting ancestral genetic clustering, not fixed rules.
Lip shape itself does not significantly affect speech or dental development. Lip seal (the ability to close the lips comfortably) is more relevant to dental positioning. Genetics also influences jaw size and teeth positioning through related craniofacial genes, so families with similar lip structures often also show similar dental patterns, but the lip shape per se is not the driver.