I often find that the certification of "naturalness" in one's choice is meant to validate that option and show others that their choices are unnatural and invalid. Frankly speaking, I don't give a flying shit about how natural or unnatural my choices are in relation to the evolution of my species. I don't classify my sexuality and the expression thereof under "mating habits." I do not reference the Hominid Timeline when determining the structure and function of my relationships and how many I should have. Your argument - no matter how cogent and well cited - is wasted on me.
My response to you is, "Big fucking deal."