Exact Doppelgangers Are Extremely Rare
The word doppelganger comes from German: "double walker". In folklore it's your exact twin, out there somewhere. Science says an exact copy is extraordinarily unlikely.
In 2015, Teghan Lucas and Maciej Henneberg at the University of Adelaide measured faces from nearly 4,000 people and asked how likely it was that two would match on eight common facial measurements (things like the distance between the eyes and the width of the mouth). Their estimate was less than one in a trillion. With about eight billion people alive, that suggests very few true doubles, if any.
Human faces may even have evolved to be unusually varied. A 2014 study by Michael Sheehan and Michael Nachman found that facial traits vary more between people than other body measurements do, and that the genes behind them show signs of selection for diversity. Being recognisable seems to have mattered.
But Close Lookalikes Are Common
Exact matches are rare, but you don't need an exact match to be someone's lookalike. People notice resemblance in overall impression: similar face shape, similar eyes, similar brows. That's a much looser test.
Think of the birthday problem. In a room of just 23 people, there's a better than even chance that two share a birthday, because you're looking for any match, not a specific one. Lookalikes work the same way. You're not asking whether one particular person looks like you, but whether anyone does. With billions of faces, the answer is almost certainly yes.
Lookalikes Can Share DNA
In 2022, a team led by Manel Esteller in Barcelona studied 32 pairs of unrelated lookalikes photographed by the Canadian artist François Brunelle for his "I'm not a look-alike!" project. Face recognition software confirmed that 16 of the pairs scored as similar as identical twins.
When the researchers analysed their DNA, those 16 pairs shared many more common genetic variants than random pairs of people, including variants linked to face shape. They were also more alike in some traits beyond the face, like height and weight. In other words, some doppelgangers look alike partly because they happen to share some of the same genes. The study was small and mostly of European ancestry, so it's a start rather than a final answer.
Why You Probably Have a Famous One
Celebrities are a small, specific set of people, but there are enough of them to cover a lot of face space. Ollie's index holds more than 5,000 living celebrities from many countries, with between 2 and 12 photos each, over 40,000 photos in total.
Each of your photos is compared with all of them. The model then takes each celebrity's single closest photo to yours. With that many people and photos, there's nearly always someone close. When the Ollie team compared all 5,000+ celebrities with each other, the closest pairs scored in the range two photos of the same person usually reach. See celebrities who look alike, according to an AI.
Read more: The Most Commonly Matched Celebrities, and What It Says About Facial Geometry
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Why Your Match Might Surprise You
- It can cross ethnic lines. Facial structure and the categories people use don't always line up, so your closest match may come from a background different from yours.
- It can cross generations. Ollie includes living stars who've been famous for decades. See matching a celebrity from another era.
- It can cross gender. If you switch the gender setting to everyone, the closest face may be of a different gender.
- It might not be who friends say. People judge resemblance by hair, expression and style. The model measures structure. See why people say you look like someone.
How to Find Your Celebrity Doppelganger
- Take a clear, front-facing photo in soft light, from about 1.5 metres.
- Upload it to Ollie.
- Look at your top five and what they have in common.
- Repeat with two more photos. The celebrity who keeps appearing is your doppelganger.
And if you want to know whether a friend or relative is your real-life double, the compare faces tool scores how alike two photos are.