Some molecules exist in two forms that mirror the right and left hands. Often, the molecular ‘lefties’ perform useful biochemical functions in our bodies. At the same time, their mirror-image ‘righties’ may be less effective or, in some cases, cause undesirable side effects. The 2026 Nobel Prize in Chemistry has been awarded to French chemist Henri B Kagan and Japanese chemist Kenso Soai for their discoveries regarding how to produce molecules with a preferred handedness.