Whether you’ve experimented with psychedelics or not, you’re probably aware that their effects can be wildly unpredictable. Psychedelic experiences vary from person to person, from drug to drug, even from a person’s first encounter to the next.

Now, researchers are one step closer to identifying what makes one person’s experience different from someone else’s—though we are still worlds away from fully understanding how a drug will affect an individual.

Classical psychedelics act on 5-HT2A receptors—a type of serotonin receptor in your brain. Activating 5-HT2A receptors causes hallucinations, mystical experiences, sensory disturbances, and many of the other common effects of psychedelic drugs.

But not everyone’s 5-HT2A receptors are the same, and according to new research, your unique 5-HT2A receptors determine how you experience psychedelics. A recent study out of the University of North Carolina at Chapel Hill School of Medicine found that genetic variations in 5-HT2A receptor genes have a say in the efficacy and potency of LSD, mescaline, 5-MeO-DMT, and psilocin (the active form of psilocybin, the hallucinogenic compound in mushrooms).

The researchers noted that receptor differences were “modest,” but certain variations seemed to produce marked alterations in response. For example, two identified gene variants resulted in a 7-fold decrease in psilocin’s potency, and another gene variation resulted in a 9-fold increase in mescaline’s potency. Each variant that produced a change in response was drug-specific, and no one variant had the same effect on all four drugs tested.

This information could be useful for informed consent once psychedelic therapies become treatment options. If a gene test lets a patient know that a drug will make them trip nine times harder than everyone else, it’s likely that they would want that information before finalizing their treatment plan.

For future study, the research team suggests pairing patients who have specific variants with the drugs that the variant alters, to bring more insight about the potential benefit of psychedelics as medical therapies.

A lofty goal of psychedelic research aims to identify common threads that may predict how a person will experience a particular drug. Some companies are taking it a step further, experimenting with novel compounds to standardize the effect or even skip the trip altogether. For now, research like this brings us closer to understanding these compounds as potential therapies.