Sometimes, resemblances between parent and child or siblings can be uncanny. Other times, such resemblances can pop up between aunt and niece or grandfather and grandchild. And still, other times, resemblances don’t exist at all.
One child may look like one parent, and their sibling may look like the other parent. Sometimes, certain facial traits seem to jump from one generation to the next repeatedly.
All of these outcomes lead us to wonder what impacts facial features. What part of our DNA is responsible for the structure and physical features that make us unique? And how much do other factors like our environment and our diet come into play?
Genetics and Facial Features
Genetics obviously plays a dominant role in our facial features. How else would we look so much like our family members? Still, many questions about how it all works remain.
“We know some parts of the genome that influence facial features, but our understanding is far from complete,” says John R. Shaffer, a professor of human genetics and oral and craniofacial sciences at the University of Pittsburgh.
Shaffer, along with Seth Weinberg, co-director of the Center for Craniofacial and Dental Genetics at the University of Pittsburgh, have uncovered around 200-300 genes that influence facial features, but that’s just a small percentage — around 14 percent — of those that likely play a role. We don’t yet know the full portion of the genome that plays a role in facial features, but we do know that it’s a lot and that some genes likely have more influence than others.
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How Genes Affect Facial Development
Heritability studies that use identical versus fraternal twins show that genetics may play as much as 80 percent of a role in what our faces look like, says Shaffer. Our facial features are made of highly polygenic genes, meaning it’s hard to say that this gene develops the nose and that one the lips because many different genes play a role.
Additionally, researchers have seen quite a bit of overlap in the portions of the genome that impact facial morphology and those that influence brain morphology. “This reflects the biological crosstalk of a growing brain and face during development,” Shaffer says.
It’s also unclear whether a mother or father has a larger influence on facial features because this hasn’t been adequately studied, says Weinberg.
But, whoever has more of an impact, development starts early. “Most developmental biologists would say that the face starts to emerge during the fourth week of development,” says Weinberg.
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Does Environment Influence Facial Features?
Other factors, such as environment, also play a role in facial features, says Benedikt Hallgrimsson, a professor of cell biology at the Cumming School of Medicine at the University of Calgary. Research has shown that kids who are malnourished, for example, look different from kids who are not. “People in general tend to look older and taller when they’re malnourished,” says Hallgrimsson.
Some environmental factors, such as pollution and toxins, may also play a role, even before birth. During pregnancy, a child may be exposed to a host of toxins that can cause changes to facial features. “Genes can even influence whether a person is exposed to environmental factors that, in turn, influence the face,” says Shaffer.
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Why Family Members Look Alike
But with so many genes involved, how can we still look so much like our family members?
“How is it that you have thousands of segregating genes influencing the shape of your nose or the overall shape of your face, and yet we can still say things like ‘in our family, my son has his grandmother’s nose,’” says Hallgrimsson. Somehow, it all comes together to make these features that are sometimes nearly identical.
So, while family resemblance makes up the majority of our facial features, the interplay between our genes and how they shape what our faces will look like is far from understood.
Read More: The 2-Million-Year-Old Human Family Tree
Article Sources
Sara Novak is a science journalist based in South Carolina. In addition to writing for Discover, her work appears in Scientific American, Popular Science, New Scientist, Sierra Magazine, Astronomy Magazine, and many more. She graduated with a bachelor’s degree in Journalism from the Grady School of Journalism at the University of Georgia. She’s also a candidate for a master’s degree in science writing from Johns Hopkins University, (expected graduation 2023).
