About 5 weeks ago I found, growing in an outdoor planter of old soil, two seedlings. They were from last year, when I had an auto Northern lights that "nannered". Not wanting to seed the whole tent, I removed the plant and left it in my garden, and let it grow. I produced seeds, but I didn't bother to keep them. Apparently some fell into the potting soil, and in March I found the two seedlings growing in an empty pot outdoors. I rescued them and put them into my tent with my photo grow. They got about 4 weeks of 19/5 light, then I flipped the tent. The autos are now 5 weeks old and flowering, they're both female, as one would expect from a nanner plant. I will keep a close eye on them, but I'm retty sure the original plant nannered because of stress.
As said, there is more than one way that plants get seeded, one is from a true male, another is a true hermie (balls not nanners), you don't want seeds from hermies, as the chances of the progeny being hermie is high, there is also stray pollen from someone elses nearby grow, and you never know what you'll get from that. Then there's nanners, those seeds should be female.