There isn’t much of a consensus on this. Some people think it’s due to greater muscle dexterity on one side of the face, others say one eyebrow is dominant in the way that one hand is dominant, while others argue that there’s a genetic component to it.

It might be a combination of all three of these factors, or perhaps none of them at all – there’s no definitive answer, unfortunately. However, if it’s a skill you’d like to improve, with a bit of practice, you can apparently learn to raise both eyebrows independently.

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Asked by: Jennifer Bruce, via email

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Authors

Dr Nish Manek is a GP in London. She completed her medical degree at Imperial College and was runner-up in the University of London Gold Medal. Manek has also developed teaching courses for Oxford Medical School, and has penned articles for The Guardian and Pulse magazine.