It's not eliminating one half. I'd suggest a definition of two people instead of one man and one woman. It's not duplicating either... it's not marrying clones. If you want to consider balance how do you know how feminine or masculine each person is; it's making an assumption that a man has traditionally male with a male mind-set and a woman is traditionally female with a female mind-set; or that their roles within a marriage or within a family will be corresponding. By the way, there are in actuality three sexes, which although usually goes unrecognised does not mean it isn't reality.<quoted text>
Updating it? How do you "update" it by eliminating one half of it, and duplicating the existing half? There's only two sexes. Marriage is a union of both of them.
Why limit it to couples? Marriage, throughout human history has been either monogamous, or polygamous. Is it fair to deny those who love more than one, marital recognition?
Again, why limit it to couples? Why maintain certain restrictions at all? If two men/women can marry in certain states, and those same states also allow first cousins to marry, why prohibit same sex siblings from marrying? There is no need to maintain such a restriction.
Are you trying to get me to trip over my own feet by bringing in multi-partner marriage and incest? What's your view?
Multiple partner marriage happens now in certain religions. These relationships also happen without marriage and outside of a religious reason.
The unacceptance of incest relationships is yes, for the family to be a simple and safe place without blurring lines; not that it couldn't work easily enough providing only adults are involved. Yes, it is a constraint of interbreeding as certain diseases increase their potency with close kin mating; but barring that...