In a 2004 New York Times opinion piece, Professor Don Browning of the University of Chicago said this of same-sex parenting: [W]e know next to nothing about its effect on children. Large-scale studies unmarked by major flaws simply had not been conducted, in part because same-sex households are a distinct minority in the United States. As of 2005, fewer than 0.4% of American children lived in households headed by same-sex couples.

Eight years later, what do we know? Same-sex households are still a minority, according to the New Family Structures Study. The NFSS highlights two other salient facts about these households: (1) many are poor and/or minority households (associated with increased risk of divorce), and (2) almost all are, technically, bisexual households. Typically, one parent moved in with a same-sex partner after divorcing or separating from the childs other biological parent.

In other words, most people entering same-sex relationships have already experienced instability in their sexual and emotional life. Giving a relationship the sanction of church or state wont infuse it with a stability it doesnt possess.

Not only have many persons in same-sex relationships suffered from the instability of a previous relationship, same-sex partnerships are naturally more tenuous than man-woman marriages. As I noted in a recent post on the MARRI (Marriage and Religion Research Institute) blog:

Man-woman marriage is built on a peculiar other-centeredness; it demands that two people who are polar opposites learn to live together. Paradoxically, this tension helps create stability. By nature, a same-sex relationship lacks this tension.

What are the consequences of instability? The first is easy: cohabitation (often with multiple partners) instead of marriage. In Sweden, Spain, the Netherlands, and other nations that legally redefined marriage between 2001 and 2006, only a fraction of homosexuals took the option in some cases, only a fraction of a percent. In Massachusetts and Vermont, the story is similar. Across the United States, a large body of research indicate[s] that few homosexual relationships achieve the longevity common in marriages.

The second is obvious: divorce. In the past, same-sex couples who got a slice of the marriage pie immediately wanted their share of the divorce market. In South Africa, couples who were first to wed under a 2006 law also won the race to divorce court only a year later; two Toronto lesbians who wed in 2003 separated after only five days, petitioning successfully in 2004 for a judge to overturn Canadian law so they could divorce. Or take Los Angeles, where 2008s historic first same-sex couple divorced this summer although they had been together for 18 years! Lest we think these cases are exceptional, of the same-sex couples who did marry in Sweden, males were 35% more likely to divorce than heterosexual couples, while lesbians were up to 200% more likely.

Cohabitation and divorce both have significant negative effects on child well-being. Since marital instability is a commonly reported cause of divorce, should we place even more children at risk by legally redefining marriage to include same-sex partnerships?