By analyzing people with similar faces, but genetically unrelated, from a DNA point of view, it was found that strong facial similarity is associated with shared genes.
The paper explaining this finding appeared in the journal Cell Reports.
“Our study provides a rare insight into human similarity, showing that people with extremely similar faces share common genotypes, while being different at the level of the epigenome and microbiome,” says Manel Esteller, lead author of the study, from the Research Institute of Leukemia Josep Carreras in Barcelona, Spain.
“Genomics groups them together, and the rest differentiates them,” says Esteller.
People with similar faces now know each other more easily
People with similar faces identified online as virtual “twins” or “doubles”, who are not genetically related, have proliferated thanks to the expansion of the World Wide Web and the ability to exchange images with people all over the planet.
In the new study, Esteller and his team set out to characterize, at the molecular level, random human beings who objectively share facial features.
To do this, the researchers recruited human “doubles” from the photographic work of François Brunelle, a Canadian artist who, since 1999, has been obtaining photographs from around the world of people who look alike. The scientists obtained images of the heads of 32 pairs of similar people.
The researchers determined an objective measure of pair similarity using three different facial recognition algorithms.
In addition, participants completed a comprehensive biometric and lifestyle questionnaire and provided saliva DNA for multiomics analysis.
Similar not only on the surface
“This unique set of samples allowed us to study how genomics, epigenomics and microbiomics can contribute to human likeness,” says Esteller.
Overall, the results showed that people with similar faces have similar genotypes but differ in DNA methylation and microbiome landscape. Half of the similar pairs were clustered together by all three algorithms. Genetic analysis showed that 9 of these 16 pairs clustered together, based on 19,277 common single nucleotide polymorphisms, they write Medical Xpress.
Moreover, physical traits, such as weight and height, as well as behavioral traits, such as smoking and education, were also correlated within pairs. Taken together, the results suggest that shared genetic variation is not just about similar physical appearance, but can also influence habits and behavior.
“We have provided a unique insight into the molecular features that can influence the construction of the human face. We suggest that these determinants correlate with both the physical and behavioral attributes that constitute human beings,” says Esteller.
The study could be useful in medicine
Some limitations of the study include the small sample size, the use of 2D black-and-white images, and the predominance of European participants. Despite these limitations, the findings may provide a molecular basis for future applications in diverse fields such as biomedicine, evolution, and forensics.
“These results will have future implications in forensic medicine, such as reconstructing a criminal’s face from DNA, and in genetic diagnosis: the photograph of the patient’s face will already give you clues as to what genome he or she has,” says Esteller.
“Through collaborative efforts, the ultimate challenge would be to predict the structure of the human face based on the individual’s multiomic landscape,” the researcher concluded.