As the annual sprout-eating ritual approaches, Anna Perman explains why you either love them or hate them

Name: TAS2R38

Location: Chromosome 7

Length: 1,143 bases

Role: Codes for PTC taste receptor

Site of action: The tongue

It is often said that there is no accounting for taste. Well actually there is. Taste is one of the few subjective experiences for which there is a relatively neat genetic explanation.

Some molecules in food have shapes that lock into proteins on the surface of your tongue. That interlocking tells a nerve to fire, sending a signal to your brain that you have tasted sugar, salt, bitter, sour or umami.

But if you don't have the gene variant that codes for the functioning taste receptor, you can eat as much as you like of the molecule it has evolved to interlock with and you won't know a thing about it.

There is one gene controlling taste sensitivity that scientists have characterised in a lot of detail – the catchily named TAS2R38 gene. This gene makes a protein that interlocks with a chemical called PTC (phenylthiocarbamide) and gives the taste sensation of bitterness.

PTC isn't usually found in the human diet, but it is very similar to chemicals found in brassicas such as brussels sprouts and cabbages. Because of this, scientists have suggested that the ability to taste or not taste PTC might explain why some people hate sprouts, and some people love them.

Ironically, the man who discovered this property of the chemical didn't have a working copy of the TAS2R38 gene. In 1931, Arthur Fox was in his laboratory pouring powdered PTC into a bottle, creating a cloud of the stuff. He was oblivious to the horrible odour, but the chemist on the next bench started complaining.

Intrigued, Fox decided to investigate why some people can taste PTC and others can't. He got his friends and family to try a little bit of it and tell him what they tasted. What he found was intriguing: he could predict very accurately whether a person would or wouldn't be able to sense PTC by looking at how their family had reacted to it. So this ability was very tightly linked to people's genetics.

This was back in the 1930s and 40s, well before genetic fingerprinting would become possible, and so for many years PTC was used for paternity testing. They assumed that if your father can taste PTC very strongly, and you can't taste it at all, chances are he isn't your father. Of course it's not completely reliable. Taste is subjective and can be weakened by other things such as smoking, age and what you habitually eat and drink.

It wasn't until 2003 that scientists managed to locate the exact gene responsible, giving those of us who hate brussels sprouts a neat, genetic explanation for why we should never have to eat them ever again.