Comment: <<There are many that think the very definition of male or female are simply cultural projections that have no basis on reality.>>

That's a pretty marginal view. Gender and sex are two different things. One's sex is the body determined by sex chromosomes. Gender is the brain's sexual identification.

Marriage is a cultural product. It's also a theological construct. The United States was quite deliberately designed to be a secular republic, hence the legal formulation of marriage isn't contingent on theological constructs.