Hermaphroditism (or monoecious mutation, whatever ya wanna call it) in Cannabis is a survival mechanism. It is triggered by stress; the plant senses that it is not going to procreate so it forms opposite sex flowers in order to pollinate itself. This insures 2 things - survival of the species and propagation of the hermie tendency (which solidifies survival of the species). I have never seen a male go hermie before, but I hear it happens. Doesn't make much sense to me because the males develop flowers first, spew their pollen and within days afterward they lose vigor and die. No time to form and mature a bean. Since it is a genetically contolled event I'm sure it does happen from time to time. I'd like to know if it is controlled by one gene or a combo of interdependent genes. I think the latter is more likely since some plants just won't hermie no matter how badly they are stressed.
Since it IS a survival mechanism I am of the belief (I can't find absolute proof) that most if not all females have the ability to mutate in this way. Simply introducing light during the dark periods of the bud cycle can often induce it. It's known as light poisoning. I do this to stress females before I use them in breeding - if they hermie they get thrown out of the program. Other environmental stressors can also induce it such as drought and chronic over/underfeeding.
Chemical treatment with ASA (aspirin), GA, and STS (silver thiosulfate) can also induce the mutation, but to say that "most of so called "hermaprodite" plants are descendant from gibberillic mutation" is pretty far fetched since the mutation has been around since the plant has been on earth and seeds and fibers of Cannabis have been found at excavation sites of human communities dating as far back as 6000 years ago (source: Ed Rosenthal). I doubt they knew anything about GA manipulation or genetics
I'm not a botanist, but I was required to take 2 semesters of botany in college. I've been an avid grower of anything green since I was about 10 and pot since I was 18 (Nixon was pres).