The vast majority if available strains via seed are poly hybrids crossed with other poly hybrids. There's very little standardization and there will be several phenotype expressions in any given pack of ten seeds.
That said, most of it will be fairly potent and different hybrids will express different highs. Pure sativas are extremely difficult to grow indoors and require the most patience as well as some extremely advanced techniques to be successful. This is because Sativas are typically from tropical to sub-tropical environments.
Another issue is hermaphroditism where a plant expresses both sexes. This is problematic when the desired crop is seedless females flowers. Breeders have made this problem worse by producing feminized seeds (seeds that are all female). The good breeders produce these seeds by stressing a female plant with colloidal silver in order to inhibit ethylene biosynthesis within the plant, resulting in male floral expression. The seeds produced from mating such a "reversed" female will be all female and will not produce hermaphrodites so long as spontaneous hermaphroditism is not an issue in the lineage of the parent plants.
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