By Luke Sholl


Some of the best memories are those parties where someone starts passing around a bong. Before you know it, the room is filled with dank smoke and everyone is having a good time. Except, of course, for that one person. The one who has taken too many hits and is convinced they are having an out of body experience.

While this would usually descend into some laughing and joking at their expense, it turns out they may not be able to help the fact that cannabis affects them differently. It is true that your overall tolerance, state of mind, and even physical fitness play a big part in how you react to cannabinoids entering your body. There is, however, one difference that unites all cannabis users: a unique genetic structure.


Our DNA defines who we are. Whether we have brown or blond hair, are short or tall—every one of us is slightly different. Our genes are passed down through the combination of DNA provided by our parents. For the most part, portions of our DNA will be copies of our parents' genetic code. Unless, however, there are genetic mutations in our DNA. Not the kind that lets you swing from rooftop to rooftop or turn invisible, but the type that can make you feel the effect of weed more profoundly.

Research[1] has shown those mutations can extend to a particular gene that influences cognitive ability when THC is present. Those with a “functional polymorphism” in the COMT Val gene experienced greater memory impairment from THC, while carriers of the COMT Met gene were unaffected. The reason that cannabis is so susceptible to variations in our DNA lies in the way the substance interacts with our body.

COMT Val Gene and COMT Met Gene


Our endocannabinoid system is made up of endocannabinoids (endogenously produced cannabinoids) and a vast network of cannabinoid receptors located throughout our immune system, digestive organs, central nervous system, and specific areas of our brain. Endocannabinoids can produce similar effects to their phytocannabinoid cousins (THC, CBD). Depending on the genetic structure of the cannabinoid, and the location or type of receptor, biological effects vary. That's why THC gets you high, but CBD doesn't. Tetrahydrocannabinol agitates a different series of receptors.

Imagine the endocannabinoid system as a switch. If the switch was only activated by THC when you smoke cannabis, you would get high. Sounds simple enough. Now add in several switches all in different locations. Each one now only activates depending on particular cannabinoids being present. When you imagine consuming marijuana in this way, it is easy to see why people can behave so differently. Cannabis involves flicking multiple switches in the endocannabinoid system, all of which will be influenced by variations in DNA, much like the COMT gene above.

A study published in 2016[2] found that those rare genetic mutations we mentioned, well, they also impact the endocannabinoid system. The preliminary findings showed that “rare genetic variants” in the endocannabinoid system caused some patients to produce higher levels of endocannabinoids. Their increased presence could lead to better coping mechanisms when it comes to anxiety and depression.


The difference provided by our parents’ DNA and the chance of minor mutations means everyone, and we mean everyone, will react slightly differently when smoking cannabis. There will, of course, be generalisations across the effects.

Those effects can include increases in appetite, a sense of euphoria, bloodshot eyes, and lethargy, to name but a few. However, with so many factors feeding into the way we feel when we smoke, the tipping point between being okay and being too high is slight. Some research[3] suggests gene variation could increase the risk of psychosis in cannabis users. Many anecdotal accounts also claim a feeling of heightened paranoia or anxiety when consuming marijuana. The reality is, with so many influencing variables, it is impossible to guarantee how you will react to cannabis.

It doesn't matter whether it is your first smoke, or if you are simply trying a new strain. You might even be smoking after a stressful day at work when usually you would enjoy weed in happier times. In each situation, your reaction to cannabis may change. The key is to start slow and test the waters. Once you are comfortable with how you behave under the influence, you can begin to broaden your horizons.

The next time you are the person who passes the point of no return, politely point out you cannot help it. It's partly down to your genetics!

External Resources:
  1. SAGE Journals: Your gateway to world-class journal research
  2. Rare genetic variants in the endocannabinoid system genes CNR1 and DAGLA are associated with neurological phenotypes in humans
  3. Featured news - Gene could help identify psychosis risk in cannabis users - University of Exeter
This content is for educational purposes only. The information provided is derived from research gathered from external sources.

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