To come up with the results, the researchers analyzed 3 types of cannabis plants sourced from industrial hemp growers, as well as ditch weed. They also studied cannabis samples obtained from the National Institute on Drug Abuse. They then studied the genetic markers specifically THC:CBD, then checked to see if the genetics were a reliable indicator of the ratio. It is the level of THC that helps them understand if the plant is actually cannabis or hemp, though the researchers do say that a THC-based definition doesn’t always match its biology. For this reason they suggested studying the ratio of THC to CBD.