Even though millions of American enjoy smoking, vaping or eating marijuana, there is still a lot of confusion regarding why marijuana strains are different from one another, so here is a crash course. There are two primary things that influence the structural formation of any given cannabis plant: genotype and phenotype.
The genotype is the plant’s genetic makeup. It acts as a blueprint for growth in the same way that our own DNA effects the qualities and characteristics that each of us are born with.
The other influence is phenotype. This is simply defined as the genetic traits that are expressed (or repressed) by how the environment effects the plant’s growth. Everything from color, shape, smell, and resin production are affected by the environment.
So for example you can take two identical strains of indica (the genotype), but depending on how it is grown (hydro vs soil, with/without fertilizer, etc..) will affect the phenotype of that strain and cause it to be high/low in THC, short or tall, etc. So that same strain could turn out to be completely different depending on the environment it is grown in.
Hope that helps clear up any confusion!