I came across this recently. It confirms that there's a remarkable amount of individual and racial variation in regards to how people experience smell. And because the receptors used for smelling things are the same the body uses internally, differences in olfaction should tell us something about a person's biology and how they might react to various drugs.
Quote:There is an enormous diversity in the repertoire of functional odorant receptor genes among different people. Roughly 60% of human odor receptor genes have mutated into non-functional pseudogenes in a relatively recent genomic process... These and earlier findings suggest that differing evolutionary pressures may have shaped the chemosensory repertoire in different human populations. Additional variation in the population may come from differences in gene expression. Experiments with custom microarrays specialized for detecting odor receptor genes have found that the expressed receptor repertoires of any pair of individuals differ by at least 14% [12], suggesting that polymorphisms exist not only in coding regions but also in promoter and other regulatory regions (Figure 1).
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GPCRs are estimated to account for some 50% of the targets for drugs in current use. As the odor receptors are GPCRs, the demonstration of polymorphic variation in their function by Keller et al. [5] provides strong support for the likelihood that polymorphic variation in other GPCRs has important effects on drug efficacy and side effects.
http://genomebiology.com/2007/8/11/230