Here's an article that reports a common set of events. Two people take the same medical marijuana product and have two completely different experiences. Same stuff, same dose, same everything. But way different outcomes. Why is that? To quote Facebook, it's complicated. First, the endocannabinoid receptors are different in different people (aka "receptor heterogeneity") . They grab onto THC in different ways with differing "tightness" of binding. Then CBD can affect FAAH, then enzyme that degrades cannabinoids, differently in different people.