Unrelated people who look alike have similar DNA

In a new study, researchers found that strong facial similarities are associated with common genetic variants and lifestyle traits.The findings are published in the journal cell report.

Same face but it doesn’t matter

each of7.9 billion people The people who inhabit our planet are biologically unique due to their individual DNA composition, the environment that surrounds us, and our life experiences. That said, one day you might walk down the street and run into a ‘doppelganger’ who looks surprisingly similar to you.

Recorded cases of doppelgangers – biologically unrelated look-alikes throughout history, sometimes with a dark twist.Mythology previously interpreted their existence as symbols bad luckMany doppelgängers in literature represent the ‘evil twin’, or symbol of a person’s ‘duality’.

Today doppelgangers are often a source of lighthearted entertainment. celebrity look-alike (Think singer Katy Perry and actress Zooey Deschanel) Really you wonder. I’ve acknowledged Does it matter? ”

As the use of social media platforms and other image-sharing tools grows globally, more and more people are identifying their own “virtual twins.”Canadian artist Francois Brunel His project “I’m not a look-alike” is dedicated to photographing people around the world who share similar facial features.

leading scientist Dr. Manel Esther,director Josep Carreras Leukemia Institute Barcelona used Brunel’s work to characterize random humans sharing facial features objectively at the molecular level.

“Year 2005, we discovered Twin brothers with the same DNA (also called identical twins) show epigenetic differences (chemical modifications of the DNA sequences that regulate gene expression), which explains why they are not exactly identical.” says Esteller. “In our current study, we explored the other side of the coin: people who have the same face but are not biologically related. It helped answer the long-standing question of how decisions are made.

Photographic example of the LAL used in this study. Credit: François Brunel.

Molecular characteristics of “look-alike”

The researchers recruited 33 look-alike pairs, including 42 females and 22 males, ranging in age from 23 to 78 years from Brunel’s work. To quantify objective similarity, they applied her three face recognition algorithms. “The human look-alikes studied were provided by the French-Canadian photographer François Brunel, so their designation as a ‘double’ was subjective. To make it more scientifically objective, we run 3 independent facial recognition algorithms (one by academics, one by Microsoft and one by a security company) to provide a perfect readout of your face. and can distinguish one face from another.” ester.

Participants were asked to provide responses to a biometrics and lifestyle questionnaire that explored height and weight, blood type, environment, diet, lifestyle, and relationship factors.Obtained and performed DNA samples from the cohort multi-omics Analysis focused on genetics, epigenetics and microbiome data.

“DNA was the most stable component of any sample that could be tested. All three of these factors are important for determining cell and tissue activity,” says Esteller when asked why the multi-omics approach was taken.

Similar genetic variants found in participants with facial similarities

Of the 32 pairs, 16 pairs were clustered by all three face recognition algorithms. “For many look-alikes, all three programs gave the same results. We couldn’t distinguish faces and were virtual twins!” says Estelle.

Genome-wide association studies (GWAS) Analysis of DNA from the saliva of these 16 participants revealed that 9 of these pairs were clustered at the genetic level, with 19,277 shared single nucleotide polymorphisms (a type of genetic variation). became.

When analyzed using a large GWAS database, the researchers found that the genetic sites shared by look-alikes corresponded to five categories.

• Genes previously reported to be associated with the shape and shape of the eyes, lips, mouth, nostrils and other facial features in the general population
• Genes involved in bone formation related to skull shape
• Genes involved in different skin textures
• Genes involved in fluid retention that can give different volumes to the face
• Genes of unknown function that may be related to facial features

The researchers then investigated whether similarities existed between the epigenetic profiles of the clustered pairs. Epigenetic processes such as DNA methylation are complex molecular mechanisms that alter the way genes are read, rather than the DNA code itself.

DNA methylation is one of the most studied epigenetic processes and involves the addition of methyl groups to DNA molecules. Methyl groups can prevent proteins from binding to and transcribing DNA, thus stopping the process by which genes are “activated.” The research group found that only one of the pairs clustered together by DNA methylation analysis.The same pair was also clustered during SNP analysis. The researchers believe this may be due to “underlying shared genetics.” When assessing similarities and differences in microbiomes, researchers found that only one similar pair I also discovered that it is clustered.

Regarding biometrics and lifestyle questionnaires, Esteller and colleagues found correlated results in similar pairs. He says, “It is said that our face reflects our soul. […] Not to be poetic, our lookalikes completed an extensive questionnaire to ascertain their physical and behavioral profiles. Look-alikes with high concordance in genetic commonalities with facial algorithms are not only similar in facial features, but also in terms of anthropometric features (height and weight) and personality traits (tobacco addiction, educational level, etc.). It turns out that they share other characteristics. It may be related to IQ, etc.)”

A rare insight into the human form

The study authors acknowledge that research is not without limitations. For example, a small sample size, predominantly European, and a 2D image of him in black and white is used. Nonetheless, they believe the discovery provides a “rare insight” into human similarities, suggesting that people with very similar faces share a common genotype, but epigenetic and are distinguished by microbiome profiles.

“Genomics clusters them together and the rest distinguishes them,” the researchers conclude.

Dr. Manel Esteller was talking with Molly Campbell, Senior Science Writer at Technology Networks.

reference: Joshi R, Rigau M, Garcıa-Prieto C, et al. Human Look-Alikes Identified by Face Recognition Algorithms Show Genetic Similarity. cell rep 2022. Doi: 10.1016/j.celrep.2022.111257.