Cilantro's soapiness is a difference in perception before it is a difference in opinion. A genome-wide study asked 14,604 people of European ancestry whether fresh cilantro tastes like soap to them, and found one variant, rs72921001, associated with saying yes; it held up in a separate group of 11,851 asked instead whether they liked the herb. The variant sits on chromosome 11 inside a cluster of eight olfactory receptor genes, one of which, OR6A2, is activated by aldehydes including decanal and (E)-2-decenal, two of the compounds behind cilantro's aroma, the second of them among those the paper describes as smelling soapy and fatty. The authors suspect the dislike is driven by the odour rather than the taste. The effect is real and small. That variant explains only about 0.5 % of the variation in perceiving soapiness, and the heritability tagged by common variants came to roughly 0.087, well under the 0.38 for odour and 0.52 for flavour the authors cite from a twin study. Reporting also differs by group: African American, Latino, East Asian and South Asian participants were all significantly less likely than Europeans to taste soap, South Asians by the widest margin, and women were more likely than men.