under intense light 12 hours and then a little off light from a clf or incandescent is totally negligible in my mind... I believe the survival theory just like a cockroach can have 2 sexes ,,, but I don't believe it is light leakage,,, if that were the case all my grows would be hermies because I have an 18/6 cfl grow space open and in the same room as my hps 12/12...