The Genetics Behind the Unibrow

The Genetics of the Unibrow Find more genealogy blogs at FamilyTree.comWhen we think of the unibrow, the image of artist Frida Kahlo might come to mind. Or, you might think of a Muppet named Bert that is a character on “Sesame Street”. You might have family members who have a unibrow (or have your own unibrow). A study set out to discover the genetics behind the unibrow.

The study was titled “A genome-wide association scan in admixed Latin Americans identifies loci influencing facial and scalp hair features.” It was published in Nature Communications. The study was done by researchers at the University College London. It involved more than 6,000 individuals from Mexico, Peru, Chile, Columbia, and Brazil.

The researchers were not only trying to learn about the unibrow. They were also interested in discovering the genetics involved with beard thickness, hair curl, and baldness. One unique thing about this study is that it focused on Latinos, who carry mixed European, Native American, and African ancestry. Another unique thing about the study is that it looks at common traits (in this case, regarding hair) as a way to better understand human variation.

The study reported a genome-wide association scan in over 6,000 Latin Americans for features of scalp hair (shape, color, greying, balding), and facial hair (beard thickness, monobrow, eyebrow thickness). They discovered a new gene variant that is associated with greying of hair.

23andMe has access to a lot of genetic data from customers who use a 23andMe DNA test kit. As such, 23andMe was able to use data from 56 different genetic variants to report back to customers with European ancestry their likelihood of having a unibrow (like Frida Kahlo). Technically speaking, the unibrow is actually called a synophrys. Only one of those 56 variants included in 23andMe trait report is mentioned in the University College London study.

23andMe says it has created an efficient and accurate way of collecting both phenotypic and genetic data that allows for genome wide association studies with a wide assortment of traits within large groups of individuals. From this data, 23andMe found that variants in the PAX3 gene are associated with the likelihood of having a unibrow, or a chin dimple, or upper back hair. Other variants in the PAX3 gene are associated with a syndrome that leads to deafness, facial abnormalities, and skin pigmentation irregularities.

There is something else to know about the unibrow. It is not considered to be fashionable. Many people (especially women) take as much care as they do with arranging their hair as they do with sculpting their eyebrows. In short, your relatives that do not appear to have a unibrow might have the genes variant that causes one.

Image by Ted Murphy on Flickr.

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