According to Michael Sheehan, an assistant professor of neurobiology and behaviour at Cornell University, who studies appearance variations and genetics, “there is only so much genetic diversity to go around. If you shuffle that deck of cards so many times, at some point, you get the same hand dealt to you twice.”
There is a huge number of genes that generate variety in our aesthetics, especially in our facial features. Evolution has seemed to favour a large degree of distinctiveness in the human face, more so than the difference in dimensions of our body parts such as our hands. This is to distinguish individuals in their species because, “you care who’s who,” Sheehan said.
Dr. Arthur Beaudet, a professor of molecular and human genetics at Baylor College of Medicine in Houston, says, “It’s not like you find an Asian and a European who look almost identical. You find two people from similar descents who probably do, in fact, have a fair amount of genetic sharing when you go way back.”
Similar features in related family members proves that faces are heritable. Therefore, it is plausible that strangers who resemble each other could be more related than people who look nothing alike. However, it is possibility that a reoccurring combination of genes can produce a set of doppelgangers even if they’re not related.