If you are a coffee nut, then give the credit---or blame---to your genes. Some mutations tend to lead you to choose the amount of coffee you drink.

This gene has a boring name--PDSS2. But it does something interesting. It controls how speedily your body breaks down caffeine, report experts.

A study team headed by Nicola Pirastu at the University of Trieste studied some coffee lovers, mainly Italians and Dutch. Some volunteers in far-off Italian villages as well as in the Netherlands are part of the study in which entire genomes have been sequenced and examined.

"The results of our study add to existing research suggesting that our drive to drink coffee may be embedded in our genes," first author Nicola Piratsu, the genetics researcher, said.

While the Italians love an average of two to three cups of coffee a day, the Dutch swill almost six cups a day. The Italians like espresso or strong perked "moka" coffee, but the Dutch like it filtered.

"Our results have highlighted a novel gene associated with coffee consumption," they wrote. "The identified gene has been shown to negatively regulate the expression of the caffeine metabolism genes and can thus be linked to coffee consumption."

The study found that participants with some recessive mutations tended to consume less coffee. "People with a higher consumption of coffee have a lower expression of PDSS2," the team said. Genes showing lower expression did not seem to be so active.

There were other genes too that are part of the team effort in the body to create coffee craving. However, PDSS2 does explain why some people need more coffee than others.

The study is published in Nature Scientific Reports.