One of the key arguments against gay marriage seems to be that one of the primary purposes of marriage is procreation–and that society, and therefore the state, has an implicit interest in protecting that definition of marriage. For instance, look how New York Times columnist Ross Douthat summarizes this argument in his Sunday column:
[David] Frum defended what was then the consensus conservative (and consensus national) position. Redefining marriage to include same-sex couples, he argued, would explicitly sever the institution’s connection to the two interrelated realities, gender difference and procreation, that it had evolved to address. In so doing, it would replace a traditional view of matrimony with a broader, thinner, more adult-centric view, which would ultimately be less likely to bind parents to children, husbands to wives.
There are two models of family presented here. In one model, a family is a two heterosexual parent unit, with children that are biologically related to both parents, and the primary purpose of that family is to ensure the proper upbringing of those children. In the alternate model, family is a mostly adult group of people who have come together, and the purpose of family is to provide support (financial, emotional, sexual, etc.) to the members of that group for as long as they are together.
But notice that this dichotomy leaves out most families that have ever existed in the world. Most families that have ever existed have not been two heterosexual parents raising their own children in their own household. Most family households around the world have also included grandparents, aunts, uncles, and/or cousins. They include step-children and step-parents. Why? Because until very recently, life-expectancy was short. Men died of wounds on the farm, or in wars. Women died in childbirth. And their spouses got remarried, often multiple times, bringing the children of previous marriages along with them, or sending those children to live with aunts or uncles.
Adoption has also been a common practice, through one form or another, throughout the history of mankind. Moses himself was adopted, of course, and King David grew up from the time he was a young teenager in the palace. Noble families throughout Europe during the feudal era raised each others children as a way to secure political alliances–sometimes as a form of hostage taking, sometimes as a prelude to arranged marriages, and sometimes just as a way to cement a friendship. In this country, churches would often encourage people to take in orphaned neighbor children.
The point of all of that, of course, is that being a family, even a family focused on raising children, doesn’t necessarily have anything to do with procreation. This idea that “procreation” and “child-rearing” go hand-in-hand is a 20th American century idea–and, even then, fails to describe a significant minority of actual families, even actual two parent “traditional” families.
Giving birth and raising a child are two very different things–I find it exceptionally odd that we seem to have forgotten that all of a sudden.