It is said that true hermies are more subject to producing hermies than chemically done.
But all feminized seed are made from female pollen from a hermied plant, done with CS or GS3 etc..
I had a place that produced hermies, next to a creek (high humidity), odd light cycles with never more than 2 hours direct sun at a time, shaded often, several times a day light shade cycles. I used the seed to make the next years crop and the only ones that hermied were in this same spot. Maybe I just got lucky, or maybe its not all that common, but happens. You dont hear about the ones that dont hermie,,,, I would try a seed or two,,,