Studies carried out at Northwestern University in Illinois have revealed that your choice of hot beverage may not be the conscious decision you once thought it was.

A study published in the Scientific Reports journal has suggested that in those with European ancestry, genetic variants may influence your perception of bitterness, and thus your preference for tea or coffee.

Coffee is made up of the amino acid quinine and a substance called propylthiouracil (prop for short). A person who favours coffee would not register these molecules as particularly bitter, however would generally taste greater bitterness in caffeine, making them more likely to reach for a caffeine kick.

Interestingly, the inverse was seen in tea drinkers: they would not register caffeine so bitterly, but would register quinine and prop as more bitter.

It may seem unusual that perceiving a substance as more bitter would make you more likely to choose it. Dr Marilyn Cornelis, co-author of the research from Northwestern University in Illinois, suggested that this could be due to learned behaviour about caffeine’s psychostimulant properties. If we perceive caffeine effectively, we will associate this with the ability to stay awake and therefore we’ll want more of it.  

Whilst all of our everyday choices are influenced by our environment, the amount of tea and coffee we drink (or desire to drink) is in some capacity, controlled by our genes.

You can’t, however, blame your parents for your cravings, because, due to random selection in utero, your affinity to coffee (or lack of) is completely out of your control!


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