I copy and pasted from another site the below info. I love Cilantro but have friends who can't stand it and always say it tastes like soap. I never understood that till I saw a study about it. Kind of interesting
for those cilantro-haters for whom the plant tastes like soap, the issue is genetic. These people have a variation in a group of olfactory-receptor genes that allows them to strongly perceive the soapy-flavored aldehydes in cilantro leaves. This genetic quirk is usually only found in a small percent of the population, though it varies geographically.