Why does cilantro taste like soap to some people?

The soap taste is genuinely genetic, so the people who insist cilantro tastes like dish soap are not being dramatic. Cilantro contains aldehyde compounds, and some of those same aldehydes appear in soaps and lotions. A subset of people carry variations in their olfactory-receptor genes, one variant near a cluster of smell genes has been specifically linked, that make them especially sensitive to these soapy-smelling aldehydes, so their brain foregrounds the soap note that other people barely register beneath the herb's fresh, citrusy character.

Large genetic studies, including analyses by the consumer-genetics company 23andMe, have confirmed the heritable component, though genes are not the whole story, since exposure, culture, and how cilantro is prepared also shape whether people learn to like it. Prevalence varies by ancestry, with the soap perception more common in some populations than others. There is even a partial fix: crushing or chopping cilantro thoroughly, or cooking it, breaks down and disperses the aldehydes, which is why some soap-tasters tolerate it in a blended sauce or cooked dish far better than as a raw garnish. So if cilantro ruins tacos for you, blame your receptors, not your palate.