Clarifying question: are you saying that 1% of humans don't produce either "small mobile gametes or large, immobile ones"? In that case what do they produce?
I've noticed that in the debate around 'binary' (on Twitter, I confess), some people claim that no human has ever been observed who didn't produce either sperm or ova (and never both). I'd like to know whether that's true. If it's true, then the GP's claim covers 100% of cases, not 99%.
