Doesnt have to always be under harsh conditions, studies simply prove that longer light periods, higher heats, lower humidity, and you walking into the grow room can turn plants to male/hermi.
From what I have read there is no 100% on any seed as they don't 100% decide sex until a couple weeks before they show sex.
P.S. your response means nothing to me as it's the same shit, a hermy can be just as useless as males..