Has the Genetic Heritage of Cannabis Been Lost Over the Years?

There is very little reliable scientific data as to where the thousands of present-day cannabis strains came from, and what exactly their specific genetic traits consist of.

In fact, as we learn more and more about the historic genetic lineage of cannabis, we are seeing an increasing likelihood that all forms of marijuana belong to a single species: Cannabis sativa L.

Of course, that’s not to say there are dozens (if not hundreds or even thousands) of different ways in which marijuana can “present itself” – some plants are short and bushy and provide calming, sedative effects, while other plants rocket towards the sky and resemble more of a beanstalk than a marijuana plant.

In terms of simple marijuana genetics, cannabis has 20 different chromosomes (for reference, humans have 46) with potentially hundreds of different genes existing on each one. Just like human beings, marijuana receives an individual chromosome from a single mother and a single father (cannabis has both male and female plants).


When these chromosomes combine, a unique arrangement of expressed and non-expressed genes is formed. This is why – even in a crop that’s been pollinated by a single male plant with known genetics – you can get offspring that possess wildly different phenotypes and cannabinoid profiles.

The massive increase in cannabis seed companies and the large resulting number of cannabis varieties has left a number of people in the cannabis world wondering whether we still know which genetic lines are faithful to the original genetics.


A quick search online and you can find any number of Skunks, Kush, White Widows, Hazes or anything else you want. But are these varieties actually what they say they are? Or has the genetic heritage been lost over the years.

A combination of selective breeding by humans and natural selection as the plant adapted to its various new environments led to the establishment of the earliest cannabis strains, known as landrace strains.


Emerging in places like Afghanistan, India, Colombia, Mexico and Malawi, each landrace had its own unique genetic profile and characteristics – or genotype and phenotype, to use the scientific terms. As time went on, these landraces became the forefathers for all modern strains, which have been created through countless rounds of cross-breeding and in-breeding in order to select for specific phenotypes.

For example, many of the Afghan landraces were of the Indica variety, which is known for its calming effects. Over the years, breeders have created numerous Indica strains by crossing these ancient Afghan cultivars with other varieties or with themselves, producing an array of relaxing cannabis strains. Yet while many breeders like to proclaim the Afghan heritage of their crop by naming it in honour of the country, no one is checking to see if these new strains still bear any genetic resemblance to the old landraces.

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The emergence of well equipped cannabis testing laboratories is allowing science to take its place in the genetic debate. Eventually it is hoped that genetic testing will allow botanists to identify unique markers in plant DNA which will allow us to verify genetic heritage beyond all doubt. Perhaps it will show that many modern hybrids are a blend of numerous genetic lines from different continents. For now that level of detailed genetic fingerprinting remains unaffordably elusive. But some people feel that a good general indication of genetic heritage could come from existing testing labs that have made a living from assessing THC levels in the USA legal cannabusiness. And the new DEA rules ending the DEA monopoly on providing cannabis for research purposes will stimulate more cannabis science.

A team of researchers recently analysed 30 different cannabis strains and found significant genetic inconsistencies between different samples of each strain, illustrating how years of cross-breeding has jumbled up the cannabis genomes, making it harder to find genetically trustworthy cultivars.

The study, which appeared in the Journal of Cannabis Research last year, included strains such as Bruce Banner, Flo, Jillybean, Pineapple Express, Purple Haze, and Tangerine, all of which are supposed to contain a 60:40 ratio of Sativa to Indica. Yet the team found that each of these strains had a totally different composition of Sativa and Indica genes, reinforcing the fact that many cannabis products on the market are not of the genetic stock that they claim.

Researchers are currently developing a method to provide a detailed genetic analysis of cannabis products. According to a study that appeared last year in the journal Plant Physiology, a team of scientists was able to identify the genes responsible for the synthesis of all of the cannabinoids and terpenes present in the plant, using a technique called RNA-sequencing. Having achieved this, they were then able to determine the exact genetic profile of nine different cannabis strains, revealing how the chemical composition of each cultivar is reflected in its genotype.

The medical applications of cannabis are huge, and there will be a future focus on creating varieties with specific cannabinoid and effect profiles for targeted applications. We may not have the answers yet, but with so much research going on it seems inevitable that at some point in the next decade we will be able to develop a deeper understanding of the genetic lineage of cannabis. And that will be important for us all, not just the purists that want to know the genuine origin of their stash.

Many people in the cannabis industry feel its time to let science take its part in the way we understand the genetics. Until then, for many people the best way to guarantee that you have the right buds in the jar is to grow known, consistent varieties from a trusted cannabis seed bank.

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