Anyone who looks like Queen Elizabeth II, Ernest Hemingway, Elvis or any politician can earn good money with it: doubles of famous people are in demand, both in showbiz and in the advertising industry.
But such unrelated "look-alike pairs" often have more in common than just the same facial features.
There are even similarities in their lifestyle and external features such as height and weight, in addition to numerous identical gene variants.
This is the conclusion reached by a Spanish research group in the "Cell Reports".
Sonya Kastilan
Editor in the "Science" department of the Frankfurter Allgemeine Sunday newspaper.
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An interdisciplinary team led by Manuel Esteller from the "Josep Carreras Leukemia Research Institute" in Barcelona recruited people who look confusingly similar based on a project by the Canadian photo artist François Brunelle.
A certain number of the “virtual twins” were then extensively biometrically examined and asked to fill out lifestyle questionnaires.
Sixteen out of 32 selected international couples were matched by the algorithms of three different facial recognition systems, which indicated a special match.
And from these, saliva samples were subjected to further analyzes of genetic material, epigenetics and the microbiome.
Not related, but surprisingly similar
The research team was able to rule out close family relationships through statistical calculations, although in one case a certain closeness was noticed, which apparently dates back several centuries and can be explained with the so-called founder effect, the consequences of which can be traced back to the French colonization of Canada in the 17th century were watching.
The scientists describe nine of these doppelgangers as "ultra-look-alikes", since they formed real clusters in the genetic analyzes and were similar in 3730 genes, i.e. each had the same variants or were heterogeneous in this trait;
including numerous genetic information known to influence human facial features or other physical characteristics, such as body size, hip-to-waist ratio or hair growth.
While, surprisingly, epigenetics didn't seem to matter much, as the comparisons showed.
However, aging processes naturally have an effect, for example the resulting wrinkles change a face, which is why the "biological age" and thus the corresponding biochemical change (methylation) of the genetic material is definitely decisive for the phenotype, i.e. the external appearance of a person.
But the doppelgangers not only looked confusingly similar in appearance, but also correlated in their behavior and other external characteristics: they were not only molecularly similar, but overall.
Even in terms of their level of education or typical habits such as smoking, there were also clear similarities in these aspects.
That is why the Spanish researchers are now assuming that genetic analyzes can tell a lot more about a person than just the color of their eyes or approximate height.
And that makes this current study, as small as the number of test subjects is, not only interesting for medicine or evolutionary biology, but also for forensics, should behavioral traits actually be determined using comparative studies in addition to appearance.
"A photo of a patient already gives you clues about the genetic make-up," says Manuel Esteller, which could be helpful for a diagnosis.
In any case, the Internet has millions and millions of pictures from all over the world ready for wild speculation: A portrait therefore provides a deep insight into the genome and reveals many a behavior.
Maybe that's something to think about before photographing yourself from every angle and posting those selfies.