If you drain your first coffee of the day while instantly planning for your next one, that quest for a caffeine hit might be due to your genes.
As part of an in-depth new study, researchers at the University of Edinburgh and the University of University of Trieste, Italy, looked at the DNA of around 3,000 coffee drinkers in the Netherlands and Italy.
According to the Daily Mail, the researchers asked participants to record how many cups they consumed per day, and matched the results against who out of the survey participants had gene PDSS2 - a variation that reduces the body's ability to break down caffeine.
The survey found Italian people with the DNA variation consumed, on average, one less cup of coffee per day than those without it.
While those in the Netherands where less affected by the gene difference.
Gene PDSS2 is thought to reduce the body's ability to break down caffeine, causing it to stay in the system for longer.
Those without the gene variation tend to metabolise caffeine faster, and are more likely to keep reaching for extra cups throughout the day.
Experts suspect the difference between Italian and Dutch coffee drinkers could be down to the type of coffee they are drinking.
In Italy, coffee fans prefer smaller cups like espresso, while in the Netherlands, the preference is for larger cups that tend to contain more caffeine.
Dr Nicola Pirastu, from the University of Edinburgh, told the Daily Mail, TThe results of our study add to existing research suggesting 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."
The study was published in the journal, Scientific Reports.