Your Doppelgänger is out there and you probably share DNA with them

Charlie Chasen and Michael Malone met in Atlanta in 1997 when Malone served as a guest singer in Chasen’s band. They quickly became friends, but they didn’t notice what the others around them were doing: The two men could pass for twins.

Malone and Chasen are local. They are strikingly similar, but not related. Their immediate ancestors are not even from the same parts of the world. Chasen’s ancestors were from Lithuania and Scotland, while Malone’s parents are from the Dominican Republic and the Bahamas.

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The two friends, along with hundreds of other unrelated look-alikes, participated in a photographic project by Francois Brunel, a Canadian artist. The series of images, “I’m not alike-like!”, was inspired by the discovery of Brunelle by the English actor Rowan Atkinson himself.

The project has become a hit on social media and elsewhere online, but it has also caught the attention of scientists who study genetic relationships. Dr. Manel Esteller, a researcher at the Josep Carreras Leukemia Research Institute in Barcelona, ​​Spain, had previously studied the physical differences between identical twins and wanted to examine the reverse: people who look alike but are not related. “What is the explanation for these people?” he wondered.

In a study published Tuesday in the journal Cell Reports, Esteller and his team recruited 32 couples who resemble Brunelle’s photos to take DNA tests and fill out questionnaires about their lifestyles. The researchers used facial recognition software to quantify the similarities between the participants’ faces. Sixteen of these 32 pairs achieved a similar overall score to identical twins analyzed by the same software. The researchers then compared the DNA of these 16 pairs of doppelgängers to see if their DNA was as similar to their face.

Esteller found that the 16 pairs that were “truly” similar shared significantly more of their genes than the other 16 pairs that the software deemed less similar. “These people really look alike because they share important parts of their genome or DNA sequence,” he said. That people who look more alike have more genes in common “would seem like common sense, but it’s never been proven,” he said.

DNA alone, however, does not tell the whole story of our makeup. Our lived experiences and the experiences of our ancestors affect which of our genes are turned on or off—what scientists call our epigenome. And our microbiome, our tiny co-pilot made up of bacteria, fungi and viruses, is further influenced by our environment. Esteller found that while the doppelgängers’ genomes were similar, their epigenomes and microbiomes were different. “Genetics brings them together, and epigenetics and the microbiome separate them,” he said.

This discrepancy tells us that the couples’ similar appearances have more to do with their DNA than the environment in which they grew up. This surprised Esteller, who expected to see more environmental influence.

Because the appearances of doppelgängers are attributed more to shared genes than to shared life experiences, this means that, to some extent, their similarities are simply the luck of the draw, fueled by population growth. There are, after all, only so many ways to build a face.

“Now there are so many people in the world that the system is repeating itself,” Esteller said. It’s not unreasonable to assume that you too might have a similar look out there.

Esteller hopes the study’s findings will help doctors diagnose disease in the future—if people have enough similar genes to look alike, they may share disease predispositions, too.

“There seems to be something very powerful about genetics that makes two people who seem to have similar genome-wide profiles,” said Olivier Elemento, director of the Englander Institute for Precision Medicine at Weill Cornell Medicine in New York. did not participate in the study. Discrepancies between DNA predictions and people’s actual appearances can alert doctors to problems, he said.

Esteller also suggested that there could be links between facial features and behavioral patterns, and that the study’s findings could someday help forensic science by providing a glimpse into the faces of criminal suspects known only from DNA samples. . However, Daphne Martschenko, a postdoctoral researcher at the Stanford Center for Biomedical Ethics, who was not involved in the study, urged caution in applying her findings to forensics.

“We’ve already seen many examples of how existing facial algorithms have been used to reinforce existing racial bias in things like housing and job hiring and crime profiling,” Martschenko said, adding that the study “raises many important ethical issues. “

Despite the potential pitfalls of connecting people’s appearance to their DNA or behavior, Malone and Chasen said the lookalike project, and the knowledge that we all might have a secret twin out there, has been a means of bringing people nearby. The two remained friends for 25 years. when Chasen got married last week, Malone was the first person to call. While not all people with similar DNA share such a bond, Malone said he saw Brunelle’s photographic work as “another way to connect all of us in the human race.”

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