Howdy Kiwibob, In my experience growing my nannered seeds, I have found that they are not more prone to producing a lot more of the nannered seeds. The environment, light cycles, heat and nutrient stresses are most likely going to produce more nanners than just the genetics. I have grown plants from nannered seeds that did not [produce many seeds at a;;, and some. when stressed, produced a lot of seeds. Like Rwise said :,,, free feminized seeds...". I'm on my fifth grow using nannered seeds, and every one has produced female plants with good yields (the last grow, three plants produced 14.664 ounces of bud with only about 60 seeds (still have some bud left to check}}.