On the other hand, people who are genetically too favoured may be banned from the sport - though they used no illegal performance-enhancing substances at all.

On the other hand, people who are genetically too favoured may be banned from the sport - though they used no illegal performance-enhancing substances at all. At least FIS has determined a hemoglobin limit for skiers, and UCI a hematocrit cap for cyclists. If your natural hemoglobin or red blood cell percentage is higher than the limit: tough, you can't participate.