Are Doppelgängers Really Just a Coincidence?

Lydia Wang ’26

Figure 1: Doppelgängers share an almost uncanny resemblance with one another.

Human faces and the ability to recognize different facial identities have played a key role in evolution. It has been observed that human faces have evolved to uniquely distinguish themselves from others. However, many people know someone they resemble; some comparisons are so similar that they are labeled as a doppelgänger, or a living double. Doppelgängers have been an ongoing phenomenon that people have yet to fully understand. A team of researchers led by Ricky Joshi from the Josep Carreras Leukemia Research Institute worked to further understand the relationship between genotype and phenotype —genetics vs. the physical manifestations of genetics— in these doppelgängersto understand whether or not these look-alikes are actually coincidences.

For this study, 32 look-alike pairs of individuals who had no familial connection were obtained from the photographic work of François Brunelle and then inputted into three different software to obtain an objective similarity score from 0 to 1, with 1 indicating identical images. The 16 pairs that received high scores from all three programs then took various biometric/lifestyle tests and had their saliva analyzed at three different levels: genome, epigenome, and microbiome. These measure what is encoded in DNA, how the DNA is organized (when certain genes are activated or not), and microorganisms that live within the human body, respectively. Of these pairs, nine were revealed to have shared genetic variations. Additionally, upon analysis of biometric and lifestyle survey results, various traits were also discovered to be shared within the pairs, such as height, weight, education, and smoking habits. DNA methylation patterns, which control gene expression, were also explored among each of the pairs; three (all of whom were in the top nine for similarity) clustered together, which implies an association between methylation patterns and phenotype presentation. Together, these results suggest that shared genetics may likely contribute to the phenotypes of individuals.

The results of this study may have implications that lead to a greater understanding of how genetics play a role in human attributes and personality characteristics. Although the researchers hoped to have a greater geographic scope within their samples, these findings contribute to a deeper understanding of how molecular, behavioral, and physical attributes can influence the formation of the human face.

Works Cited:

[1] R. Joshi, et al., Look-alike humans identified by facial recognition algorithms show genetic similarities. Cell Reports 40, 111257 (2022). doi: doi.org/10.1016/j.celrep.2022.111257 

[2] Image retrieved from: https://commons.wikimedia.org/wiki/File:Freddie_Prinze_Tony_Orlando_Chico_and_the_Man_1976.JPG

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