I had a lemon skunk hermie on me late in flower last year. It was a plant I kinda ignored and it was defiantly stressed for water at times. As I understand the factors that cause a plant to hermie are stress and genetics

Stress can be caused by many factors like my water stressed lemon skunk or lighting issues. Many years ago I read an interview in High Times with a hash maker from India. He said in the interview that if he sees signs of a hermie he pulls on the root system slightly. Just enough shock the root system. The claim was that this would stop the plant from going hermie. I have never tried this.