A collection of photos of genetically unrelated look-alikes, along with DNA analysis, revealed that strong facial similarity is associated with shared genetic variants. The work appears on August 23 in the journal Cell reports.
“Our study provides rare insight into human resemblance by showing that people with extremely similar faces share common genotypes, while they are discordant at epigenome and microbiome levels,” says lead author Manel Esteller of the Josep Carreras Leukemia Research Institute in Barcelona, Spain. . “Genomics brings them together, and the rest sets them apart.”
The number of people identified online as virtual twins or genetically unrelated duplicates has increased due to the expansion of the World Wide Web and the ability to exchange images of humans across the planet. In the new study, Esteller and her team set out to characterize, at the molecular level, random human beings who objectively share facial features.
To do this, they recruited human doubles from the photographic work of François Brunelle, a Canadian artist who has been obtaining worldwide images of lookalikes since 1999. They obtained portraits of 32 lookalike couples. The researchers determined an objective measure of similarity for the pairs using three different facial recognition algorithms.
Additionally, participants completed a comprehensive biometric and lifestyle questionnaire and provided salivary DNA for multiomics analysis. “This unique set of samples allowed us to investigate how genomics, epigenomics and microbiomics can contribute to human likeness,” Esteller said.
Overall, the results revealed that these individuals share similar genotypes, but differ in their DNA methylation and microbiome landscapes. Half of the similar pairs were grouped together by the three algorithms. Genetic analysis revealed that 9 of these 16 pairs clustered together, based on 19,277 common single-nucleotide polymorphisms.
Additionally, physical traits such as weight and height, as well as behavioral traits such as smoking and education, were correlated in look-alike pairs. Taken together, the results suggest that shared genetic variation is not only linked to similar physical appearance, but may also influence common habits and behavior.
“We have provided unique insight into molecular features that potentially influence the construction of the human face,” Esteller said. “We suggest that these same determinants correlate with the physical and behavioral attributes that make up human beings.”
Among the limitations of the study are the small sample size, the use of 2D black and white images and the predominance of European participants. Despite these caveats, the results may provide a molecular basis for future applications in various fields such as biomedicine, evolution, and forensics.
“These results will have future implications in forensics – reconstruction of the criminal’s face from DNA – and in genetic diagnosis – the photo of the patient’s face will already give you clues as to what genome they have,” said said Esteller. “Through collaborative efforts, the ultimate challenge would be to predict the structure of the human face based on the multiomics landscape of the individual.”
This work was funded by the governments of Catalonia and Spain, as well as the Cellex Foundation.
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