Telegraph article by Matthew Moore (10 Nov 2008) ‘Odourprinting’ could be used to identify people:

Human beings could one day be identified by our smells, according to research that shows individual “odourprints” cannot be masked by diet. [...] Eating powerful foods such as chili or garlic may change how we smell, but it does not disguise our underlying genetically-determined aroma, tests on mice have shown. Creatures who were given strong-smelling foods were still recognised by their peers.

Information via We Make Money Not Art… Regine’s delicious bookmarks.