It is the genetics, the whole point of the light you have is to be able to get the plant closer to the light without causing problems. There are just some plants that no matter how well you treat them the still turn hermie. You can still get a good yield from these plants, remove all male parts. I had a strain from greenhouse seeds and it was a hermie, but after taking males part off, it produced a considerable yield. If I was you I would invest in some more cuttings from elsewhere or buy some seeds.