Some people can taste certain chemicals in some vegetables much more strongly than other people and really don’t like them.

https://en.wikipedia.org/wiki/Supertaster

Supertasters are individuals whose sense of taste for certain flavors and foods is far more sensitive than the average person.[1] The term originated with experimental psychologist Linda Bartoshuk and is not the result of response bias or a scaling artifact but appears to have an anatomical or biological basis.

Reports of variations in human taste perception date back to 1888.[5] The major advance in understanding human taste variation came in 1931 with the discovery of “taste-blindness” specifically for thiourea compounds, when Arthur L. Fox, a chemist at DuPont, discovered that some people found phenylthiocarbamide (PTC) bitter, while others found it tasteless.[6][7]

Fox describes the event:

Some time ago the author [Arthur L. Fox] had occasion to prepare a quantity of phenyl-thio-carbamide, and while placing it in a bottle the dust flew around in the air. Another occupant of the laboratory, Dr. C. R. Noller, complained of the bitter taste of the dust, but the author, who was much closer, observed no taste and so stated. He even tasted some of the crystals and assured Dr. Noller they were tasteless but Dr. Noller was equally certain it was the dust he tasted. He tried some of the crystals and found them extremely bitter.[8]

https://en.wikipedia.org/wiki/Phenylthiocarbamide

Phenylthiocarbamide (PTC), also known as phenylthiourea (PTU), is an organosulfur thiourea containing a phenyl ring.

It has the unusual property that it either tastes very bitter or is virtually tasteless, depending on the genetic makeup of the taster. The ability to taste PTC is often treated as a dominant genetic trait, although inheritance and expression of this trait are somewhat more complex.[2][3]

https://www.compoundchem.com/2014/12/04/brusselssprouts/

At this point, you’re probably wondering what this has to do with brussels sprouts. Whilst the compounds PTC and PROP aren’t found in the vegetables, they both contain within their molecular structure a thiocyanate group (nitrogen, carbon and sulfur bonded in series) which is thought to be related to their bitter taste. This same group is also present in compounds called glucosinolates, which occur naturally in brussels sprouts, as well as broccoli, cabbage and kale (collectively known as cruciferous vegetables). The glucosinolates are thought to form part of the plant’s defence systems , for example against diseases and creatures that feed on the plant. Additionally, the breakdown products of glucosinolates, the isothiocyanates, also contain the thiocyanate group within their molecules.

So why is this structural similarity significant? Well, there seems to be a strong association between the ability to detect the bitter taste of PTC and PROP and a sensitivity to the bitterness of these vegetables. Of course, it’s not the case that sensitivity to PTC and PROP automatically implies a dislike of cruciferous vegetables; other factors may also have an effect, such as a person’s particular flavour preferences. However, if you’re a brussels sprout hater, you can now suggest a potential chemical reason for your dislike if you’re ever berated for your perceived vegetable prejudice.

When did you last try sprouts? They’ve bred the bitterness out of them.