People who look alike share similar DNA
Scientists estimate that about 80% of the genes we carry are involved in building the structure of our faces and hence the way we look. And so we’ve always suspected that, potentially, if you find someone who looks very like you, chances are you have a lot of the same genes in common. Now scientists have confirmed that’s the case, and it unlocks the possibility of predicting what someone might look like, based just on their genetic code. Julia Ravey spoke to Manel Esteller, from Josep Carreras Leukaemia Research Institute (IJC) in Barcelona, who’s been comparing people who aren’t related but nevertheless look very much alike…
Manel - We started with different levels of complexity in cells to know what is the main contributor to having similar faces; genetics, epigenetics - that is the regulation of DNA - and the microbiome - how many bacteria? What type of bacteria? It's difficult to give a number, but you can imagine that around 1000 to 2000 genes are relevant for the shape of our face.
Julia - And there are people out there who aren't twins. They're not even related as far as they know, but they look really, really similar. So why is this?
Manel - This is our study. Our study looked at these people that look very similar, but they're not related because we have gone back hundreds years, we have seen that these people that share very similar faces are not in any way related by family. And in this case, they share these genetic variants that relate to the shape and volume of our mouth nose, eyes, cheeks, but also to our height and weight.
Julia - Why do you think that there are these commonalities between people that aren't even related?
Manel - It's difficult to know why, but the most logical explanation for us is that this is happening by random chance. So there are now so many people in the world that they share these particular genetic sequences that relates to the shape of our face. Now we have more ways to find these people because internet and all the apps, the young generations and teens are now able to catch another person that looks like them.
Julia - Beyond the face, were there any other characteristics that these individuals had in common in terms of their genes?
Manel - There were other parts of the body that were related in this case. And also some other traits, like for example, the use of tobacco, the smoking, and to be right or left handed, they were shared. So this probably goes a little bit beyond the face.
Julia - And you sometimes see people in couples actually look very similar. Sometimes we're attracted to people who look like us. So is there any need to be worried if you're in a relationship with someone who looks a bit like you in terms of potentially having some recessive traits that might come together in offspring to produce something which isn't overly great?
Manel - In theory, from a genetic point of view, it's better that you mix up with somebody that is different. In fact, some people that live together, they start looking similar and because they live in the same environment, you know, the same contamination or the same job, they eat the same things. So it's possible that recent conversions later in humans, these things are not inherited, they are acquired. They relate a lot of them to epigenetic changes, the content of the microbiome, and these are things that relates to our lifestyle.
Julia - So if I find someone who looks like me say on the other side of the world, I shouldn't be worried that I've got a long lost twin?
Manel - If it's perfectly identical, you can worry, but being perfectly identical, it's very difficult. So they look alike, but they're not, of course, perfectly identical. You can only be a copycat if you share 100% of your genome.
Julia - What are the consequences of this work?
Manel - Maybe now from DNA, we can think of constructing a face and this can be important in forensic medicine, for example, to find somebody responsible of a crime, just from the DNA, to be able to draw a face. So maybe now there are some data you can start doing that.