Lesson time!
Cannabis has genotypes and phenotypes. Genotype refers to the cultivar(people also incorrectly call it, "strain,") of the cannabis plant. Or, the genetic makeup of the cultivar. Both mean the same thing.
Nowadays, there is enough evidence to prove environment makes cultivars grow differently. The different variations that show up due to this is what is known as phenotypes. Since genotypes map out the potential growth patterns and characteristics of the plant, the environment the genotype is in will make different traits show up.
So, say we have 2 plants from the same batch of seeds, like you do. Same genotype(cultivar), same seed run, same everything. Sisters, basically.
We keep them in the same exact environment, with the same exact amount of light, nutrients, etc. A month after germination, one is growing faster than the other. This means the plants are different phenotypes, due to displaying different growth patterns in the same environment.
Let's take it one step further. Let's say these plants are flowering. One plant might be done, but the other still looks like it needs another week or two. This is more proof that the two sisters are different phenotypes.
Finally, you get to smoke some after a great dry and perfect cure! The plant that was done faster has a decent taste, but the one that took longer is five times more tasty! That's due to environment triggering different gene sequences of the genotype and making them dominant.
I hope this helps.