Yes. You could blame that savage hangover on the seven tequila shots you did last night. But we have a much better scapegoat. Genetics.

The basic cause of a hangover, of course, is ethanol (the alcohol in our drinks), which causes dehydration and urination and probably some really bad text conversations. But other factors, including diet, blood sugar levels, and even your immune system can play a role, and a recent study shows that genetics might be influencing those factors.

Actually, probably half of your predisposition to a terrible hangover has to do with your genes. A study of 4,000 Australian twins found that “genetic factors accounted for 45 percent of the difference in hangover frequency in women and 40 percent in men.” We’re gonna have to guess that study was really, really fun at first and then got terrible once the hangovers set in, and instead of ordering a greasy breakfast, participants were forced to fill out questionnaires and have those sticky science wires stuck to their throbbing heads.

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Twins are extremely useful in all sorts of genetic studies since they’re genetically identical (the monozygotic kind, that is). If twins with different external circumstances drink the same amount of alcohol and report consistently similar hangover symptoms, researchers can confidently conclude there’s a genetic link.

In a way, it’s kind of terrible news. Some of us may be genetically doomed to a life of hangovers (or forced to adopt that silly grown-up moderate drinking thing). But really, the information is incredibly useful, not only so you can feel less rage at the friend who had exactly as much to drink as you did yet wakes up will an uncorrupted will to live. The study also indicated that the genetic predisposition to a hangover is linked to a greater propensity to drink—to drink enough to get the hangover in the first place, which, theoretically, “could contribute to future research on alcohol addiction.”

And then there’s the whole “figuring out the mystery of the hangover” thing. Not that we don’t know what a hangover is on a totally brutal physical level. But the causes have been a tad murky. We know congeners have a role (technically, compound “impurities” that give complexity to darker spirits but can also jack up that headache to 11). In fact, one research study had 95 people aged 21 to 35 drink either Absolut vodka or Wild Turkey bourbon. Both spirits had the same alcohol content but the bourbon had 37 times more congeners than the vodka. While each group was equally foggy the next day, the bourbon drinkers had worse hangovers than the vodka drinkers.

But beyond the basics, it looks like your DNA might play a role in how much you want to drink, and how much your body punishes you for drinking. Kind of unfair.