“Cannabis is an interesting domesticated crop with a long history of cultivation and use. Strains have been selected through informal breeding programs with undisclosed parentage and criteria. The term “strain” refers to minor morphological differences and grower branding rather than distinct cultivated varieties.

The “sativa” and “indica” lineages used to describe cannabis throughout the industry are based on postulation that sativa strains originated from European hemp cultivars, while indica are from potent, resinous Indian cannabis but given the use and trade of the plant in ancient times, the exact origin is unknown and these may not be distinct species. Comparisons of cannabinoid contents of these classifications have shown that the THC content can be identical between these two classification groups.”   https://www.nature.com/articles/s41598-018-31120-2