Totally.
So, just like everywhere on this planet where reproduction happens in a species that has a distinct male and female contribution (such as us and marijuana), nature has allowed for a built in attempt at survival in how these genes are shared. What genes are expressed can relate to a plant's (in nature) ability to survive its environment. After millions and millions of years, nature has developed a method of ensuring that the maximum variety possible is expressed from any individual life-form to increase the possibility of the survival of that species in an ever-changing environment. As this process has continued, certain genes have proven to be beneficial which allowed for their carriers to live longer, healthier, more reproductive lives. Thus different species, and within them different families and categories emerged. And within them, there still exists this variety because whenever two parents combine DNA, it will result in a 50/50 add mixture that is different each time as. This is why twins that come from two separate eggs are never identical even though they came from the same male and female parents. Only twins that result from a single fertilized egg (thus the same exact genetic code) are identical. In fact, if you could clone the male sperm so that those two eggs were fertilized by a genetical identical sperm, they would still not be identical, in fact they could still produce male and female offspring. As soon as a different egg or pollen/sperm is involved you have instant variety! So, when you get a seed form a seed bank, it came from one particular female egg (not just a plant, but a distinct ovule) which was fertilized by male spermatozoa (one particular grain of pollen). Even if they use a single male or a single female to generate all these seeds, the fact is each male and female contribution is a random mixture of that plants particular genetic code.
It could have a dominant gene for, say, displaying purplish hues in certain environments (you would see it represented as P when talking about genetics (capital P because it is dominant, so P would mean it would show purple, p would mean it wouldn't)). That plant could have the code Pp (one dominant and one recessive - which would still result in a purple tendency since the dominant gene will overpower the recessive gene; Pp, PP, and pP all would = purple; while pp would = not purple). So when this plant creates an ovule, it will distribute the P and the p genes randomly throughout. If that plant, even though it gets purple, has a male pollenate this egg with pollen with the p gene, the resulting seed will not show purple colors (this could be true even if the father plant is a purple-showing plant, since it could also have the Pp code which means it has the genes for both, he just happened to pass along the recessive p gene which, matched with the females p gene would create a non-purple offspring genetically)
So even though plants belong to a certain strain, there still exists a large measure of variety and mixture amongst the genes. Certain dominate traits begin to show themselves creating something like sub-categories of that certain strain referred to as phenotypes. Essentially they represent physical, noticeable characteristics that are determined by the expression of certain dominant genes within a strain. Especially when dealing with hybrids where a mixture of sativa and indica genetics are in play, you often wind up with one or more phenotypes that each lean more towards the sativa or indica parentage depending on what genes were present in the particular pollen and the particular ovule that created each one of them. So with one female plant fertilized with one male, you can get a multitude of different gene expressions based on the distribution of each plants genes amongst their contributions to the reproductive process and the random way in which they combine and form a unique genetic profile. It can take quite a view generations to stabilize and weed out (pun intended) the undesired traits until you get the dominance of particular genes to become prevalent. This is why different races and even different peoples within the different ethnicities are identifiable as part of distance categories of people on this planet. This happened to all of our ancestors as they settled in areas and began to reproduce. Certain genes began to be expressed while others weren't passed on due to a multitude of various factors. It created wondrous variety and amazing adaptations within our own species that has improved the survivability of these different families within the human race. Incredible right!?
This is why clones are the ideal way to maintain a particular genetic profile you like. Seeds are always representative of two distinct parents, and the distinct genes that their contributions had when they combined to make the seed. Of course, you have the hermaphrodite exception where a plant fertilizes itself. But still, that plant has a variety of genes that are randomly distributed throughout its ovules and the pollen it develops out of a response to stress/desperation. So, while the seeds from this plant will be "feminized" (meaning there is no Y chromosomes available in its genetic code so they can't make boys), the seeds will still represent a certain distribution of genes that are expressed based on their dominance or recessiveness compared to other genes, and so you get distinct variation in that scenario.
So, if anyone ever posts on your thread something like "That isn't a real [fill in the strain]", they don't quite realize that the only "real" copy is a clone. Unless you have a cut from the original OG plant or the Blue Dream or whatever (does anyone? highly speculative), what you really have is a plant that represents the mixture of genes that have come from a massive variety of parentage and unique profiles of plants within the strains used to create the strain in question. It could be true that one particular plant might have some dominant traits that show up frequently within that strain due to selective breeding, but a seed from the same mating that produced seeds that grow plants that look like the strain is "supposed" (desired) to can also produce plants that are just as much that strain, but express different genes. Essentially different phenotypes. Breeders take the phenos they like and try to further develop them using male plants that also demonstrate these desired traits. The result will always be variety - but more plants with the desired traits will result if parent are selected carefully.
Hopefully that didn't confuse more than help as I might have just confused myself