Regnerus's study, the New Family Structures Study, interviewed 15,000 adults aged 18-39 and asked dozens of questions about their lives, including whether their mother or father had ever been involved in a same-sex relationship. Among those whose parents had been involved in same-sex relationships, the outcomes were significantly worse than for children raised by married mothers and fathers. Even after controlling for factors such as age, race, gender or the gay-friendliness of the state in which they lived, those raised in homes with one (or more) gay parents reported that they experienced more depression, ill health, unemployment, infidelity, drug use, trouble with the law, sexual partners, sexual victimization, and unhappy childhood memories.
Critics protest that the NFSS is comparing the gold standard -- intact married-parent homes -- with families that have experienced many levels of instability. That's true. Only a tiny percentage of the adults in the NFSS study spent their entire childhoods with their gay parent and a committed partner. The rest had seen their parents' marriages dissolve, either because of sexual orientation issues or for other reasons or they never formed and they lived in a variety of household configurations during their formative years. Regnerus does not deny this saying, "One notable theme among the adult children of same-sex parents ... is household instability, and plenty of it. ... While we know that good things tend to happen ... when people provide households that last, parents in the (study) who had same-sex relationships were the least likely to exhibit such stability."
Same-sex marriage advocates argue that once gay marriage is universalized, GLBT couples will be able to offer the same kind of stability that married heterosexual couples do. That may turn out to be true. But a) it may not, and b) it doesn't disprove the evidence NFSS has compiled that earlier "no difference" studies were excessively cheery.
Regnerus declines to advise about whether same-sex marriage is a good idea or not. But he does make a point that his critics have entirely missed: gay marriages, even if they achieve stability and durability, will continue to lack the "kin altruism" that marks biological parents. Though it isn't essential -- many adoptive couples succeed wonderfully without it -- the evidence suggests that the biological tie between parent and child is important in securing the very stability so necessary for children to thrive. Far, far too many heterosexual married couples divorce or fail to marry at all these days. And yet the stability of married, male/female parents outstrips that of adoptive, stepparent or co-habiting parents. If same-sex parents achieve a comparable level of stability, they will achieve what adoptive, stepparent and co-habiting couples have not.