To understand why some people end up with the same result in life’s facial features lottery despite not being related, it helps to know why not everyone looks alike. After all, human beings are from the same species — doesn’t it make sense for people to look alike, in the same way cats, dogs, and mice seemingly share the same faces?

According to the Guardian, human DNA does follow a set of rules when it comes to forming faces; however, it’s not a secret that scientists have managed to crack. Part of the reason is that the interaction between genes (epistasis) is a complicated process with “complex and unpredictable” effects (via the Conversation). Furthermore, the variations among human faces aren’t overstated, but noticeable enough to make a difference. The distance between the eyes, thickness of the lips, or position of the nose on the face are just a few examples. In 2013, scientists found facial differences encoded in human’s non-protein-coding (or “junk”) DNA (via the Genetic Literacy Project).

While genes do affect human facial features, they’re not the only factor responsible for why people have different faces. The 130 or so chromosomal regions believed to affect facial development can only do so much, after all. In fact, they only account for about 10% of facial shape variation; other biological and non-biological factors such as hormones, diet, age, and even sun exposure have roles to play in this as well.

Admit it: The thought that you might have a doppelganger is both fascinating and frightening. After all, no matter how cool the idea of having a non-related lookalike may sound, it opens the doors to potential cases of mistaken identity. This underscores just how important individuality is for humans — and why having unique facial features matters more to Homo sapiens than any other species.

In a 2014 paper published in Nature, researchers reported a greater degree of variation in humans’ facial dimensions than in their hands. Furthermore, there are more genes connected to facial appearance than in any other aspect of the human body’s development. Humans seem to have evolved specifically to be good at telling each other apart, as the capability to distinguish individuals requires not just observable differences among members of a group, but also the brainpower to process them. Compare that to how other animals tend to use either their ears or noses to identify each other even in pitch-black environments (via UC Berkeley).

This all circles back to how humans are a highly social species. As Dr. Michael Sheehan explained to LiveScience, distinct faces help people to identify allies and avoid threats as needed. Or, as UC Berkeley population geneticist Michael Nachman puts it: “The idea that social interaction may have facilitated or led to selection for us to be individually recognizable implies that human social structure has driven the evolution of how we look.”

Down syndrome is a developmental disorder that manifests in children with 47 chromosomes instead of 46 (the extra being a copy of chromosome 21). Interestingly, patients with this genetic condition share particular facial and cranial traits, regardless of their country of origin. According to How Stuff Works, this enables medical professionals to swiftly diagnose the condition. As it turns out, it’s just one of thousands of genetic disorders that facial shape and other characteristics can point to.

As the Genetic Literacy Project explains, a chromosome 21 trisomy (or the occurrence of an additional chromosome) affects the development of recognizable physical traits. This is because the genes involved in this process also influence skull and organ development. Other examples of genetic disorders that distinct facial characteristics can reveal include Turner’s syndrome, Angelman syndrome, and Fragile X.

In a 2020 article published in the Conversation, Seth M. Weinberg and John R. Shaffer shared how their examination of 8,000 DNA samples revealed “a high degree of overlap between the genes involved in facial and limb development.” They believe that this is linked to why patients with certain genetic disorders tend to have both distinct facial characteristics and malformed hands. They also revealed that genes influencing facial shape development may have something to do with cancer development as well.

If your doppelganger does indeed exist, there’s a pretty good chance that you’ll find them living in the same country, city, or town as you, for the simple reason that people sharing the same ethnic background tend to have similar facial characteristics.

According to the Genetic Literacy Project, people have generated computerized facial composites of folks from specific ethnicities. This has revealed some shared characteristics within certain ethnic backgrounds that manifest in generated “average faces.” LiveScience explains that people within the same ethnic group share a larger set of genes than people outside their group; this influences not just facial traits, but also skin color, hair color, and other physical characteristics.

Admittedly, it’s neither easy nor completely fair to define ethnicity simply by genetic traits alone. After all, increasing global emigration means that formerly isolated racial groups have now started to interact and reproduce with one another, passing their genetic traits on to their offspring. However, it does stand to reason that people with shared genetic characteristics tend to live in the same groups, which means a higher chance of lookalikes emerging within them. This is especially the case if you’re part of a massive ethnic group like the Han Chinese or the Hindustani, both from Asia. Oh, and don’t forget that scientific evidence points to all of humanity emerging from Africa, anyway (via LiveScience).

Fortunately, you no longer have to wait for a random encounter just to find out if you have a doppelganger. There are various online resources that can help you find and identify your unrelated twin.

One of the most popular tools is the Twin Strangers Project. According to ABC 7, the project, which analyzes facial characteristics of user-submitted photos to process potential matches across the world, started out as a challenge among friends to test the theory that “there are 7 people in the world who look exactly like you.” Another app, TwinsOrNot, takes the reverse approach, but with similar driving principles: After feeding it two profile photos, the app compares the images and assesses just how similar the faces in the photos are (via Windows).

Still, just because someone out there has a face that looks like yours, doesn’t mean you can easily exchange places with them. Facial similarities notwithstanding, even the slightest difference in eye color, height, or nose shape will be obvious to anyone who knows and cares about you. Remaining blissfully ignorant about any possible doppelgangers isn’t so bad — especially if it means no cop will mistakenly arrest you for a crime you didn’t commit.