More than half of America’s population over 18 drinks coffee every single day, and according to the National Coffee Association, caffeine lovers in the United States drink an average of 3 hot cups of Joe daily. New research indicates that the amount of coffee we drink may actually be influenced by genetics.

The study from researchers at the University of Edinburgh's Usher Institute reports that one certain gene, called PDSS2, appears to curb an individual’s coffee drinking. The findings show that people with a DNA variation in the gene tend to consume fewer cups.

So, how does it work? According to experts, the PDSS2 gene reduces the ability of cells to break down caffeine, causing it to stay in the body for longer. People with the DNA variation tended to consume fewer cups of coffee than people without it.

Dr Nicola Pirastu, a Chancellor's Fellow at the University of Edinburgh's Usher Institute, said: "The results of our study add to existing research suggesting that our drive to drink coffee may be embedded in our genes. We need to do larger studies to confirm the discovery and also to clarify the biological link between PDSS2 and coffee consumption."

To reach this conclusion about PDSS2 and its connection to caffeine tolerance, researchers examined the genetic information from 370 people living in a small village in southern Italy and 843 people from six villages in northeast Italy. Participants completed a survey, which included a question about how many cups of coffee they drank each day.

The study was originally conducted in a group of 1,731 people from the Netherlands, and scientists at the Usher Institute simply recreated it for more diverse results. The outcomes were similar from both studies, but the gene’s effect on the number of cups of coffee consumed was slightly lower in Italy.

There are a number of explanations for this discrepancy. Researchers reported that it’s because people tend to drink smaller cups, such as espresso, in Italy, meanwhile in the Netherlands most prefer larger cups that contain more caffeine overall.

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