The genetics behind your Christmas dinner

Christmas is the time to eat, drink and be merry, but how will you decide which festive treats to indulge in this year? Whether it’s a really bad sweet tooth or a hatred of spicy food, we all have our own specific rules when it comes to what we will or won’t eat, but how did we develop these flavour preferences and why do they vary so much from person to person?

Genetics of taste

A child looking unhappy about eating a Brussels sproutLike nearly all of our characteristics, nurture influences which foods we like and dislike. For example, some of our culinary preferences develop while we are still very young and depend upon flavours that we may have been exposed to in the womb or via breast milk. However, research into our perception of flavours suggests that nature plays the biggest role in dictating our taste preferences. Different groups of genes encode receptors on the tongue, which detect sweet, salty, bitter, sour and umami tastes. The sensation of taste is created when signals from these receptors are combined with signals from odour receptors in the nasal passages. Variations in these ‘taste genes’ can alter the way we perceive flavours.

One of the best-known examples of this is people who have a particular variant of the TAS2R38 gene, which leads them to taste some bitter flavours much more intensely than other people. This is due to the fact that the TAS2R38 gene strongly influences our ability to taste some bitter-tasting chemicals. For example, PTC (phenylthiocarbamide) is a synthetic chemical that people can taste either strongly, weakly, or not at all, depending mainly upon their genetic make-up.

Interestingly, whether or not you can taste PTC may influence some of your food choices this Christmas. As a general rule, people who can taste PTC will avoid sprouts and red cabbage as they contain chemicals that taste very similar to PTC. There is also some evidence that PTC tasters might be the first ones diving for the Christmas pudding; people who can taste PTC often prefer food and drinks with higher sugar content.

The ability to taste PTC is explored within the ‘A Question of Taste’ workshop that we run for A level groups at Nowgen. Students are intrigued to find out that some cannot taste PTC at all, and our experience suggests that those ‘non tasters’ tend to be the sprout lovers!

Scientists also believe that some common food preferences have developed as an evolutionary advantage. Most of us find calorie-rich foods quite hard to resist – but this may be more than us craving fatty foods that we shouldn’t eat! Humans evolved in environments where food was not readily available and poisonous or toxic foods were a constant threat. Therefore it’s highly likely that a preference for calorific foods provided an evolutionary advantage and was passed on from generation to generation. So if you can’t keep your hands off the Christmas chocolates this year, just blame your ancestors!