NorthShore’s Renowned Genetics Expert Weighs in on New Study

By Carolyn Starks

Perhaps the only genetic phenomenon more fascinating than twins is the doppelgänger—the idea that there is a stranger in the world who looks just like you.

Now, a new study has taken our captivation with look-alikes to a new level. Published last month in the journal Cell Reports, the study found that strangers with similar faces likely have similar DNA. 

DNA is the most unique and identifying factor about each of us—it helps determine what color your eyes are, how tall you are, and how likely you are to have certain health problems. Even so, over 99% of DNA sequences are the same among all people. It is the remaining 1% that explains much of what makes each person unique.

Photo credit: Francois Brunelle
Photographic examples of look-alikes used in this study

The Research Process

The study authors obtained headshots of 32 pairs of look-alikes from the photographic work of François Brunelle, a Canadian artist who has been obtaining worldwide pictures of look-alikes since 1999. They also answered a lifestyle questionnaire and provided saliva for DNA analysis. 

The researchers determined an objective measure of likeness for the pairs using facial recognition software. Sixteen pairs achieved facial recognition scores similar to scores of identical twins analyzed by the same software.

The Results

The researchers found that unrelated people with extreme look-alike faces do, in fact, share common genotypes. 

They also found that physical traits such as weight and height, as well as behavioral traits such as smoking and education, were correlated in look-alike pairs. Taken together, the results suggest that shared genetic variation not only relates to similar physical appearance, but may also influence common habits and behavior.

Is it common sense that strangers share similar DNA or does this new study reveal new discoveries? Are these strangers related or is it chance that they share DNA? 

We asked Peter J. Hulick, MD, Chair of Personalized Medicine for NorthShore, for his insight into this research that is making international headlines.

Would the doppelgängers in this study be considered related?

“Related” has a societal and biological construct, but yes they may be more “related” than other people. We all have an ancestral tie genetically, so it’s not surprising that there is an underlying shared genetic component to physical traits. 

Do we all have a doppelgänger? Could there be three or more people who are extreme look-alikes?

Statistically, we probably all have a doppelgänger, and yes, there could be three or more people who are extreme look-alikes.

A limitation of the study was the small sample size. Even so, what stood out to you about this study?

This study elicits a discussion about nature versus nurture, which is always an interesting aspect of genetics. Another interesting aspect is the use of facial recognition software and its future use, for example, as a diagnostic tool for diseases or syndromes. Could this study expand on other traits that have a polygenic risk? Will these traits help us understand behavioral relationships because we understand the genetic mechanism behind it? It’s a playful look but gives insight into facial genetics and possibly the biology of the aging process.

Are you interested in genetic testing to inform your health?

For more information, visit the Mark R. Neaman Center for Personalized Medicine where we are tailoring patient care through genomic research and technology.