DNA analysis and a collection of photographs of genetically unrelated lookalikes have shown that great facial likeness is tied to shared genetic variations.
The article is published in Cell Reports in August 2022.
The growth of the World Wide Web and the ability to share human images globally have led to a rise in the number of genetically unrelated individuals who have been recognised online as virtual twins or doubles.
Esteller and his team’s goal in the new study was to characterise random people with objectively similar face traits on a molecular level. They did this by hiring human impersonators from François Brunelle’s photographic collection, a Canadian photographer who has been gathering images of lookalikes all around the world since 1999. They acquired the headshots of 32 similar-looking couples. Utilizing three distinct facial recognition algorithms, the researchers came up with an objective measure of resemblance for the couples.
According to senior scientist Manel Esteller of the Josep Carreras Leukemia Research Institute in Barcelona, Spain, their study offers a rare insight into human likeness by demonstrating that people with extremely similar faces share common genotypes but are discordant at the epigenome and microbiome levels. Genetics groups them together, whereas the rest differentiates them.
“This unique set of samples has allowed us to study how genomics, epigenomics, and microbiomics can contribute to human resemblance,” Esteller says.
The subjects also submitted saliva DNA for multiomics analysis and completed a thorough biometric and lifestyle questionnaire.
Overall, the findings showed that although these people had comparable genotypes, they have different DNA methylation and microbial landscapes. All three methods clustered together half of the lookalike couples. Based on 19,277 common single-nucleotide polymorphisms, genetic study of these 16 couples showed that 9 of them grouped.
Additionally, there was a correlation between lookalike pairs of physical characteristics like height and weight as well as behavioural characteristics like smoking and education. Together, the findings imply that shared genetic variation may affect common behaviours and behaviour in addition to similar physical appearance.
“We provided a unique insight into the molecular characteristics that potentially influence the construction of the human face,” Esteller says. “We suggest that these same determinants correlate with both physical and behavioral attributes that constitute human beings.”
The study’s sample size is limited, it only uses 2D black-and-white photographs, and the majority of the participants are from Europe. Despite these limitations, the research may offer a molecular foundation for upcoming applications in a number of disciplines, including forensics, evolution, and healthcare.
“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 says. “Through collaborative efforts, the ultimate challenge would be to predict the human face structure based on the individual’s multiomics landscape.”