I had my first plants in the ground in 79 Hammer and all i and my friends grew were sativas and i smoked lots of different imports threw the years until they ended and i didn't see the hermaphrodites you clearly did.
I grew a few different Thai lines non hermd on me non of my flowers were seeded unless i allowed a male to pollinate to make fresh seed that was my experience.
The bulk of what i loved to grow and smoke were Thais.
Im sure Sam and the Haze brothers had many as well.. This was extremely common in cannabis in the 70s through the late 80s when we all grew the seeds from imports. You must be one lucky SOB to never get herms.