I have heard that too - whether it is true or not - I do not know. You could always run an experiment - may not be definitive but at least you'd have some empirical evidence.
I have heard it and used to go 24\0 all the time and get like 80% hermie so i took the advice of a frnd and went 17\3\1\3 and so far i got all fems (this is the first grow i tried it on and an in early veg stages but 4 outa 4 are fem)maybe works maybe just luck i don't know and have clones now so won't know till next time i grow from seed
If a plant is vegging for 3 wks and show no sex yet is lighting is on 24, and you take cutting of the clone and flower it and come out male, woud switching the lighting back to 18/6 to the mother plant induce female?