On Tuesday, the father-son duo of Steve Harrington and Jean-Ralphio Saperstein renewed our interest in doppelgängers. The pair, which actually consists of Stranger Things actor Joe Keery and Ben Schwartz of Parks and Recreation, posted a series of Twitter photos together, fueling the viral conspiracy theory that there was some secret cross-show parentage going on. More importantly, it forced us to consider whether living look-alikes actually exist.

Science has some ideas, but it can’t provide a conclusive answer. With similar features and hair that won’t quit, Keery and Schwartz certainly appear to be swoon-worthy doppelgängers, even if the so-called “family line” wasn’t purposefully planned by their show’s creators. While body doubles run amok and every friend-of-a-friend has had a “oh my god they looked exactly like me” moment, the chances that people can look exactly alike are very, very low. Experts haven’t ruled out the possibility, but they can’t confirm that doppelgängers really exist, either.

What is more likely to explain their nearly identical looks is good old-fashioned genetic diversity. To be more exact, it comes down to a lack of genetic diversity: Any two random people are likely to share 99.5 percent of their gene sequence. The Executive Vice President of the American Society of Human Genetics, Joseph McInerney, tells Women’s Health that the remaining 0.5 percent of the human genetic sequence consists of 16 million base pairs of DNA. Mutations in those base pairs is what leads to individual variation in humans, but there’s always a chance individuals will have similar mutations, resulting in individuals looking very similar.

Lookalikes are more common in people who come from a similar ancestral background. While person A and person B may live thousands of miles away now, it doesn’t mean their their great-great-great grandparents didn’t kick it. In particular, similar ancestry means an increased likelihood of common characteristics, like eye color and stature. Schwartz and Keery aren’t exactly dopplegängers, but is sort of possible that there is a familial connection between them somewhere down the line.