You might have a friend, relative, or co-worker who can guzzle multiple cups of coffee each day while you feel overly buzzed after just one. If you find yourself wired on less than 16 ounces of the stuff, it might be more than a personal preference: Caffeine tolerance could be part of your DNA.

According to a paper published in Scientific Reports this week, a genetic variant known as PDSS2 has been detected in people who prefer to stop at just one or two cups. Researchers examined 1207 coffee drinkers in Italy and found that those who had the variation drank an average of one fewer cup per day than those who didn’t. Another 1731 subjects in the Netherlands produced similar results.

Why the discrepancy? PDSS2 might contribute to an inability to break down caffeine as efficiently as people who don't have the gene. That means the stimulant effects will linger, requiring less coffee to get the same boost as someone downing multiple cups.

The study’s authors say further research will be required to make a more conclusive link. For now, it might be safe to say that a percentage of the population can get the same kick out of one or two cups that someone gets out of twice as many—and without having to use the bathroom nearly as often.

[h/t Los Angeles Times]