By Andy Coghlan Read a related editorial: Where do nutrititional supplements fit in sport? THE Beijing Olympics have long been tipped as the event where athletes might first try modifying their genes to boost performance (New Scientist, 15 January 2000, p 24). “Gene doping” is attractive because it prompts the body to make hormones that are indistinguishable from the ones we make naturally. That makes cheats harder to spot. So will gene doping make its debut at Beijing?