The doppelgänger phenomenon is more than a supernatural coincidence.
DNA analysis of unrelated people who look alike has revealed that their facial similarities are rooted in shared genetic variants.
With the advent of social media has come an increase in bizarre incidents of two complete strangers who realize that they look eerily similar — despite sharing no branches in their family tree.
What was once a rarity in real life has become almost commonplace on the internet — providing researchers with a wealth of images and information that allows them to dig deeper into the mystery on a molecular level.
“Genomics clusters them together, and the rest sets them apart,” said senior author Manel Esteller of the Josep Carreras Leukaemia Research Institute in Barcelona, Spain, in a statement.
Esteller, whose new findings were published in the journal Cell Reports on Tuesday, said the study provides “rare insight into human likeness,” plus where that likeness begins and ends.
Canadian artist François Brunelle embarked on a similar study in 1999 when he set out to find and photograph pairs of look-alikes from across the globe. It was these portraits that became central to Esteller’s current findings.
Researchers recruited 32 couples from Brunelle’s project into the study, requesting each to complete a comprehensive biometric and lifestyle questionnaire and provide saliva samples for DNA analysis. The group was further narrowed by three facial recognition algorithms, revealing a group of 16 close matches.
Results would show that look-alikes tend to share similar genetic characteristics, or genotypes, and that nine out of the 16 pairs with the most closely copied faces, according to artificial intelligence, had 19,277 genetic variations in common.
The genetic similarities manifested in more ways than looks: physical traits, such as height and weight, as well as some behavioral attributes, such as smoking habits and education, also correlated between look-alikes.
However, each individual’s environment, lifestyle and other genetic factors led to their many differences.
“We provided a unique insight into the molecular characteristics that potentially influence the construction of the human face,” Esteller explained. “We suggest that these same determinants correlate with both physical and behavioral attributes that constitute human beings.”
Researchers acknowledged shortcomings in their research, including the fact that a majority of participants were Europeans, and hope their work will continue to benefit biomedicine, forensics and the study of evolution.
“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.