i am of the opinion that we don't really know for sure. there are different sides to the coin. some believe that gender is absolutely predetermined in the seed, meaning the plant is the same sex at sprout as it is at 5 weeks veg as it is at harvest. some believe that stress causes hermies. some believe that all plants are prone to hermie and it is the grower with the final say while others believe a hermie is a hermie and separate from a male or female. some believe that sex hormones are only active once a plant is mature or forced to flower. i have yet to see a study where a vegging plant had its dna extracted therefore proving what sex it is, then comparing it later to the dna when the plant is flowering. if stress truly "causes" hermies, then a simple dna test should prove it. until someone does a series of dna tests we are really all just speculating imo.