Whether you know it as cilantro, coriander or Chinese parsley, you’ve probably seen this bright green herb pop up on restaurant menus. South American, Southeast Asian and Middle Eastern dishes have been using the feathery, branch-like leaves of cilantro for centuries.

The Internet has been raging with debate about this controversial herb. Opposition groups forming on websites like “I Hate Cilantro” boast a community of almost 4,000 members that dub it “the most offensive food known to man.” On the other hand, some cilantro lovers created the “Fuck Yeah Cilantro” Tumblr to share their love for the leafy herb with the world. You can be sure that for every cilantro lover who relishes its strong, distinctly citrus-like flavor, there’s an equally opinionated cilantro hater who shudders in revulsion, denouncing its soapy and even bug-like taste.

So how is this seemingly harmless green herb capable of producing such polarized debate? According to a well-known study by behavioral neurologist Charles J. Wysocki of the Monell Chemical Senses Center in Philadelphia, we might be genetically predisposed to love or hate cilantro. Wysocki studied identical and fraternal twins’ preferences find out. Wysocki and his researchers asked pairs of twins to rate the “pleasantness” of cilantro. Interestingly, the twins tended to fall into clear-cut categories, either loving or hating it. Furthermore, only about 40 percent of fraternal twins gave like assessments, whereas identical twins’ similar ratings were closer to 80 percent. These results seem to suggest that cilantro preference may be a genetic trait, but Wysocki cautioned that there hasn’t been quite enough collection of data to reach a firm conclusion yet.

Wysocki also speculated that the dislike of cilantro stems mainly from its odor rather than its taste, hypothesizing that those who don’t like it lack the ability to detect certain chemicals in the leaf. A gas chromatograph, which separates compounds, can be used to break down the molecules in cilantro so that researchers can analyze each compound individually with both the instrument and their sense of smell. When the cilantro is heated, the soapy odor is released, followed by the more pleasant lemony smell about 10 minutes later.

Cilantro haters seem to be able to detect only the soapy smell. As Wysocki’s theory goes, cilantro haters may have different receptor genes for the protein that interacts with the more pleasant smelling compound.

While the evidence continues to grow that an aversion to cilantro may be genetic, scientists have yet to work out the specifics, such as which genes are responsible for this fierce hatred of the herb.