These total strangers are doppelgängers. A new study says they share DNA, too changing what we know about genetics.

Among family members, genetic similarities go even deeper.

Within the 0.1% that's left, about half of your DNA is shared in common with your mother, and roughly the other half comes from your father.

And it's likely that person, wherever they may be in the world, looks quite a lot like you.

When Brunelle started photographing strangers who look alike in 1999, he wasn't really interested in why it was that these people look similar — how it came to be, scientifically, that two people who weren't from the same family shared an appearance.

"What I like about my project is just to see these two people, side by side," he said.

Specifically, there's a group of about "20,000 spots in the genome" that "cluster these pairs of lookalike people together," study author Carlos García-Prieto, a cancer researcher at Josep Carreras Leukaemia Research Institute in Barcelona, explained to Insider, detailing the research he and his colleagues recently published in Cell Reports.

That's much less genetic information in common than, say, a mother and her child would have to share, but it is a statistically significant amount, which separates true doppelgängers from other strangers.

Some of the genes these pairs share in common were previously known to be associated with the shapes of people's faces, especially with the shape of the mouth, nose, eyes, chin, and forehead.

Other genetic similarities the researchers found between the look alikes are involved in the ways our bones are formed, and in liquid retention in our faces.

For the study, the scientists asked 16 pairs of Brunelle's "look alikes" — 32 people that he's photographed — for spit samples. They then used the spit to analyze the participants' DNA, noting similarities in the genes, microbiomes, and epigenetics (gene expression) of each pair.

There were stark differences in the microbiomes and epigenomes of the look alike participants, suggesting that the genetic code alone is largely what's responsible for their similarities.

"It's something that is somehow inherited," García-Prieto explained. "We were kind of surprised because we expected also a little bit of the epigenome [which determines how genes are expressed] to play a role in these similarities."

Participants with similar faces and similar genes also reported some similar habits (like smoking, for example) in common, at a rate more often than complete strangers would be expected to share such characteristics.

Brunelle's noticed the same trend during his long-term project.

"Most of them have a similarity," he said.

The photographer has clicked images of hundreds of look-alike pairs around the world, but chiefly he's captured faces in Europe and North America.

"When you put them together, then you see the differences," he said. "It's my work, it's my craft, my art to try to find: where is the likeness between them?"

The research find, though still preliminary, suggests that one day forensic detectives might be able to sample DNA from a crime scene and reconstruct a sketch of a victim or suspect.

Or, just from analyzing a patient's face, doctors might some day be able to screen for certain associated issues, for which genomic variants suggest a predisposition to disease.

"Probably lots of companies are going to become even more interested in getting this data," García-Prieto said.

Brunelle has found doppelgängers also exist through time — he has uncovered uncanny resemblances between ancient sculptures and folks who are alive right now.

But perhaps his proudest moment behind the camera so far was when he photographed the bald couple from Spain, Soto and Kaotico.

"I was blessed to be able to do that photo," he said. "That was a good pair."

The two now share even more than DNA, looks, and common interests — they got married earlier this year in Madrid, Brunelle said.