When you see me again, it won’t be me.
Imagine you are running late for a flight.
You finally board the plane, get to your assigned seat, but it’s just your luck that there is someone already sitting there.
As you politely try and tell them that they are in your seat, you realise.
This person looks exactly like me.
This is the true story of Neil Thomas Douglas and Robert Stirling who met on a Ryanair flight in 2015. They even ended up checking into the same hotel.
Even though doppelgangers are historically associated with bad luck, we are weirdly fascinated with them. A quick Google search finds many click-baity articles comparing: celebrities who look-alike, celebrity look-alikes, even celebrities who look like historical figures.
Some of these pairings are a bit of a stretch, but you would be hard pressed to find two people who were almost 100% identical, other than identical twins.
What are the chances?
Research from the University of Adelaide suggests that the likelihood that two unrelated people share the exact same face based on eight different facial measurements, is more than one in a trillion. With the worlds population at approximately 7.6 billion people, the chance of there being a single pair of doppelgangers somewhere in the world is only one in 135.
A major limitation of this study was that it relied on exact measurements. A one-millimetre difference in ear size would rule out complete likeness, even if the other seven measurements were equal. This shows that numbers alone cannot determine facial similarity.
In fact, facial recognition itself is quite subjective, just look at these people who thought they ran into celebrities. Some people may even suffer from face blindness, a brain disorder that impairs a person’s ability to recognise faces, including their own.
It’s not entirely up to genetics either.
Doppelgangers from Ireland, Niamh Geaney and Irene Adams, decided to take a DNA test, after suggestions from online video commenters that they could be related. The results showed there was only a 0.0006% chance they were full siblings, and a 0.1% chance they were half siblings. In fact they had no common ancestor up to 20,000 years ago.
It is really hard to pin down a scientific explanation for doppelgangers. Zaria Gorvett from the BBC used the infinite monkey theorem to explain the possibility. This theory states that a monkey hitting random keys on a typewriter or keyboard for an infinite amount of time will almost surely type a well-known text. So with infinite time and infinite births as populations grow, the chance of two babies growing up into similar looking adults increases.
Whatever the cause, there most likely is someone out there who could be your twin stranger, you just haven’t met them yet, and you probably never will.
For the curious: Twin Strangers