"Seriously, why on earth is anyone asking which is the 'natural' way to be?"

I just want to answer that question: one reason is the discussion which lifestyle choice is easier. For example, my friend Emilia has a food phobia -- she can't stand meat. For her, being a vegetarian is very easy (and being omnivorous would be near impossible). There is a big difference between her and some vegetarians that crave the taste of meat, but refrain from eating it for ideological reasons. She could get psychological treatment and through a long and painful process arrive at a state where meat would no longer disgust her; but it sure wouldn't be easy. It's the same thing with poly lifestyle -- for some people it just comes "naturally", they don't need to fight jealousy, they simply never have it to begin with.
But the more important reason nature pops in poly/mono discussions is that the mono people bring it in. Very often, I hear "but your relationship form is not natural!" and feel an urge to throw it back at them :-)

Sorry for commenting so late on your posts, but I just saw you through tacit and I think you're awesome :-)