Your doppelgänger acts like you, too

Who might be your doppelganger?

Photographs of four unrelated lookalike pairs included in the study.Image credit: François Brunelle LiveScience

It's likely that there's another human being with your face somewhere in the world. A recent study reveals that you and an unrelated look-alike may share more in common than just your physical appearance. Facially similar persons are more likely to share genes and engage in comparable activities, according to a study of 32 unrelated doppelgänger pairs from around the world. However, the genes that are actively expressed and the microbial ecosystems in each person's body are distinct. These "virtual twins" never really met one other in person, but were brought together because of the efforts of Canadian artist and photographer François Brunelle, who began compiling images of people who looked strikingly similar to one another in 1999. Results were published online ahead of print in Cell Reports on August 23.

"Our study provides a rare insight into human likeness by showing that people with extreme lookalike faces share common genotypes, whereas they are discordant at the epigenome [the genes which are switched on or off] and microbiome levels," senior author Manel Esteller, the director of the Josep Carreras Leukaemia Research Institute in Barcelona, Spain, said in a statement. "Genomics clusters them together, and the rest sets them apart."

Half of the 32 matched pairings were designated doppelgangers by all three facial recognition systems, and the other half completed a lifestyle and biometric questionnaire in their original languages for the study. The researchers performed DNA analysis on these 16 closely related pairs to learn more about their genetic structure. Nine of the 16 pairings were found to be "ultra" look-alikes, sharing 19,277 common genetic variations (called single nucleotide polymorphisms, or SNPs) across 3,730 genes, making them appear to be extremely related. These extreme look-alikes did not have any more in common with one another in terms of epigenetics or microbiomes than any other pair of people. It's a sobering reminder that genetics can have a significant impact on how people act, as many of the look-alikes shared not only part of their genes but also the same smoking habits, educational backgrounds, and body types.

"These findings do not only provide clues about the genetic setting associated with our facial aspect, and probably other traits of our body and personality, but also highlight how much of what we are, and what defines us, is really inherited or instead is acquired during our lifetime," the authors wrote in the study.

The fact that these genetic similarities between unrelated doppelgangers arose by coincidence is remarkable in and of itself, but the fact that Earth is rapidly reaching a population of 8 billion people makes it clear that the possible combinations of the human genome are far from endless. According to the study authors, these findings have potential applications in a variety of disciplines, including evolution, biomedicine, and forensics.

"These results will have future implications in forensic medicine — reconstructing the criminal's face from DNA —and in genetic diagnosis — the photo of the patient's face will already give you clues as to which genome he or she has," Esteller said. "Through collaborative efforts, the ultimate challenge would be to predict the human face structure," based on genes and other factors.

Source: Livescience