Our ability to detect odours – and how strong or pleasant we find them – also depends on how those detectors work in our own individual noses. We smell a fragrance like violets when a chemical called beta-ionone binds to a detector known as OR5A1. But for about half of people, that detector simply doesn't work. You'll never be able to smell beta-ionone if you're one of them, no matter how much of it is sitting in a vial in front of you.

— Read more in The great smell-off: TikTok sparks debate on American vs European noses at BBC.