Jeff Jacoby
Do kids raised by same-sex couples turn out as well as those raised by parents of the opposite sex? In recent years, the accepted answer among social scientists has been that there is no difference: Families headed by a mother and father are no better at child-rearing than those headed by two mothers or two fathers. "Not a single study," the American Psychological Association categorically declared in a 2005 brief, "has found children of lesbian or gay parents to be disadvantaged in any significant respect relative to children of heterosexual parents."

But was that conclusion -- which has been cited many times -- warranted? Loren Marks, a scholar at Louisiana State University, recently went back and reviewed the 59 studies on which the APA had relied. None of them, he writes in the July issue of the academic journal Social Science Research , "compares a large, random, representative sample of lesbian or gay parents and their children with a large, random, representative sample of married parents and their children." Most of the studies were built on small samples that were neither random nor representative. In the absence of high-quality data, the "strong, generalized assertions … made by the APA brief were not empirically warranted."

Assuming Marks is right about the weakness of the findings on which the APA's verdict was based, how many advocates of same-sex marriage or adoption by gay and lesbian parents will consider changing their view? How many would back away from their support for gay marriage in the light of anything social science might say? I'd estimate the number at, roughly, zero. Conversely, suppose Marks's paper had demonstrated that the APA's declaration was even more firmly supported than previously realized. How many principled opponents of gay marriage would change their minds? My estimate would stay at zero.

Jeff Jacoby

Jeff Jacoby is an Op-Ed writer for the Boston Globe, a radio political commentator, and a contributing columnist for