In 2010, the company 23andMe published a genome-wide association study on whether participants have "ever noticed a peculiar odor when you pee after eating asparagus?" This study pinpointed a single-nucleotide polymorphism (SNP) in a cluster of olfactory genes associated with the ability to detect the odor. While this SNP did not explain all of the difference in detection between people, it provides support for the theory that genetic differences occur in olfactory receptors that lead people to be unable to smell these odorous compounds.