Genetics makes them a Male not stress.Stress can make them a Hermie.The only thing I've heard on that front is to pick a branch and put it on 12/12 using a paper bag that can breathe or something to that effect. The only friend I have that is a regular grower with experience tells me this isn't a good idea, and the few people I've gotten advice from here all seem to agree any additional stress just increases the odds of getting a male in the first place.
edit : or what he said ^