NO diseases, no bugs, apparently no problems

Because your not looking hard enough. Check out some of what Ace Seeds is doing and shop around... There is a known problem of genetic diversity in Cannabis just not known by the grow community at large... But doesn't everyone wonder why there are soo many mutants running around. "Large populations are more likely to maintain genetic material and thus generally have higher genetic diversity.[6] Small populations are more likely to experience the loss of diversity over time by random chance, which is called genetic drift. When an allele (variant of a gene) drifts to fixation, the other allele at the same locus is lost, resulting in a loss in genetic diversity.[11] In small population sizes, inbreeding, or mating between individuals with similar genetic makeup, is more likely to occur, thus perpetuating more common alleles to the point of fixation, thus decreasing genetic diversity.[12] Concerns about genetic diversity are therefore especially important with large mammals due to their small population size and high levels of human-caused population effects.[16] A genetic bottleneck can occur when a population goes through a period of low number of individuals, resulting in a rapid decrease in genetic diversity. Even with an increase in population size, the genetic diversity often continues to be low if the entire species began with a small population, since beneficial mutations (see below) are rare, and the gene pool is limited by the small starting population.[13] This is an important consideration in the area of conservation genetics, when working toward a rescued population or species that is genetically-healthy. " Quote from Wikipedia entry on Genetic Diversity.

that example was only for trying to get a recessive trait common ... i should have explained it a bit more.. not neccessarily what is always happening.

Phenotype just means expression of various traits that are visible (less resolved, less certain, less sophisticated view of things -- it's why we used to hve "5 kingdoms" and not have 3 domains.. genetic research corrected our mistakes based on phenotypes). They share a lot of traits, because they breed for certain traits to be consistent and to remove others that are not beneficial. Plus, a lot of BS out there too -- not just numbers based on massive CO2 and lights brighter than the sun, lol... (exagerrating of course). Look up Punnett squares.. it gives an idea of what i mean... 25% of one gen come out useful, so you take them and breed them with another similar group with that recessive genes, and when you breen them you knwo have 100% that recessive trait in nex generation. it's obviousl much, much more complicated than that.. nothing of value in this context likely controlled by just 2 alleles, plus all sorts of other mechanisms at work.

Think your asking the wrong people! But good ideas! Bring them to their attention! Happy growing!