Can you be genetically related to your doppelganger?

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Look-alikes may have more in common than meets the eye. marcoventuriniautieri/Getty Images
  • The researchers genetically compared humans identified by facial recognition algorithms as lookalikes.
  • They analyzed their DNA sequences (genome), their DNA methylation statuses (epigenome) and their microbiome profiles.
  • They found that 9 of these 16 non-blood lookalike pairs had very similar DNA, but differed in their epigenetic DNA methylation patterns and oral microbiome profiles.
  • Interestingly, people with strong facial resemblance also showed similarities in other physical characteristics and personality traits.

All inherited characteristics are encoded in distinct DNA sequences, called genes, which are transferred from parent to offspring. A person’s complete set of genes is called their ‘genome’. According to Human Genome Projecthumans have between 20,000 and 25,000 genes.

In recent years, geneticists have discovered that genes can be turned on or off by chemicals and proteins that can attach to sections of DNA. These gene-regulating compounds and proteins are known as “epigenome“.

In a study published in 2005, Dr. Manel Estellerdirector of the Leukemia Research Institute Josep Carreras, and his colleagues reported that identical (or monozygotic) twins share the same DNA but may show differences in several traits, such as susceptibility to diseases, due to the epigenetic modification of their DNA sequence.

Now a new study by Dr Esteller and colleagues in the journal Cell reports sheds light on the genome, epigenome and microbiome profiles of people who have a strong facial resemblance but are not blood related.

Share DNA with your doppelganger

“The result is that these look-alike humans have similar genetic sequences and are therefore like twins, while their epigenetic and floristic profiles of microorganisms differentiate them. Interesting[ly]not only do they have identical faces […] but by having similar DNA they end up having [similarities in] other body aspects and similar personality traits too!”
— Dr. Manel Esteller

“Basically, the study shows that there is a genetic basis for facial diversity. We already knew that because faces are hereditary (i.e. you look more like your family than you [other members] of the population) and others studies with random samples […] were able to identify genetic variants in populations associated with facial features,” Dr Michael Sheehanassociate professor of neurobiology and behavior at Cornell University, who was not involved in the study, said Medical News Today.

“This study takes all of that to a logical extreme. If two people really look alike […], this means they will likely share many face-identifying genes as well. Based on how we understand heritability and the genetic basis of traits, this result was expected,” he said.

The researchers studied 32 pairs of humans identified as look-alikes by French-Canadian photographer François Brunelle.

To ensure that their naming as lookalikes was scientifically objective, the researchers ran photos of the pairs through three different facial recognition algorithms: one academic, one from Microsoft and another from a security company. For half of the look-alike pairs (16 out of 32), the three algorithms were unable to distinguish faces, confirming that the pairs were objectively “virtual twins”.

The next step was to analyze the molecular components likely to influence the construction of the human face. For each study participant, researchers determined the DNA sequence (genome), DNA methylation status (epigenome), and bacterial and viral content in oral swabs (oral microbiome).

The researchers found that 9 of these 16 lookalike pairs had very similar DNA and labeled them “ultra-lookalikes”. The 9 ultra-similar pairs shared 3,730 genes. Most of the shared genes are known to be associated with human facial features, bone and skin properties, and water retention.

“The key to understanding this finding, I think, is to keep in mind that there is very limited genetic diversity in modern humans compared to the size of our current population. The human population has really exploded over the past of the [10,000] years,” Dr. Sheehan said.

“The genetic diversity that determines features like faces today is essentially the same genetic diversity that existed in the past. […] ultimately, all humans sample from relatively low levels of genetic diversity and so there are only a limited number of combinations to be made. If you shuffle a deck of cards enough times, you’ll find that sometimes you get exactly the same order of cards.
— Dr. Michael Sheehan

Of the 9 ultra-similar pairs, only one pair had similar DNA methylation patterns, and only one pair had a similar oral microbiome. This suggests that human lookalikes differ in their epigenome and microbiome.

Study participants also completed a comprehensive biometrics and lifestyle questionnaire.

The researchers found that physical and personality traits – such as weight, height, smoking habits and level of education – were correlated in look-alike pairs, implying that a shared genome is not only linked to facial similarity, but can also influence common habits and behavior.

The correlation between shared preferences and genome similarities is not a new idea.

“People who are friends tend to have common preferences, and studies showed that friends are genetically more similar than one would expect by chance,” Dr Sheehan said. DTM.

In their paper, the researchers acknowledge that the study is limited by its small sample size, which is “due to the difficulty of obtaining similar data and biomaterials.”

Another limitation is that the study participants were mostly European, although the few Hispanic and Asian pairs studied showed the same results as the European pairs.

Dr. Sheehan said DTM that “we should expect roughly similar results in other populations, although the exact details of the associated genes may vary from population to population”.

Studies showed that African populations have higher levels of genetic diversity than non-African populations.

The results of this study could open new avenues of research. The findings provide insight into human facial genetics and have potential future applications in various fields, such as biomedicine and forensics.

In the future, Dr Esteller hopes it will be possible to infer from facial features “the presence of genetic mutations associated with a high risk of developing a disease such as diabetes or Alzheimer’s disease”..

Another potential application of these findings is in the field of forensics, where it may be possible to reconstruct a criminal’s face from DNA.

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