Like humans, they each have between 20,000 and 25,000 genes. Most genes are the same in all of them, but there will be differences in less than one per cent of them, which is what makes them unique. The science of genetics is helping them to understand what these small differences mean. The genetic test reveals how genetics have defined your inner workings – how you metabolise food groups, which micronutrients your body efficiently absorbs and which ones it doesn’t, also your capacity for endurance, speed and strength.