There can be no more contentious issue in sociology than whether same-sex couples do as good a job raising kids as married biological parents. As state after state in the US opens the door to same-sex marriage, judge after judge has affirmed the "no difference" thesis. The kids are OK. Occasionally a social science study even finds that kids do better when they grow up with gay parents.
The sentiments of California Judge Vaughn Walker, in his 2012 decision overturning Proposition 8, have been repeated numerous by judges ruling in favour of same-sex marriage:
"Children raised by gay or lesbian parents are as likely as children raised by heterosexual parents to be healthy, successful and well-adjusted. The research supporting this conclusion is accepted beyond serious debate in the field of developmental psychology."
Beyond serious debate? That's a big call. A big bluff, even.
Not long afterwards a sociologist at the University of Texas Austin, Mark Regnerus, collected data from 3,000 adults in a project called the New Family Structures Study. After some complicated number-crunching, he found that adults whose parents had a same-sex relationship have lower educational attainment than adults who grew up with both married biological parents. They were also more likely to be welfare recipients, experience depression, smoke, and be arrested.
Since this was the most comprehensive survey to date on this topic, Regnerus's article was a bombshell. His research was attacked by other social scientists and he himself was vilified as dishonest, homophobic, shameless, pseudoscientific, denigrating and delusional.
Regnerus stuck to his guns. His study had some limitations, but the data was there.
Admittedly, a number of small studies do suggest that "the kids are OK", but they tend to be statistically unconvincing. As Loren Marks, of Louisiana State University pointed out in a survey of 59 studies, most of these examined short-term outcomes, involved fewer than 100 participants and were biased toward well-educated white lesbians with high incomes, and many compared homosexual couples with single mothers, not intact families.
So the evidence is far from overwhelming.
And, as Walter Schumm, of Kansas State University, has recently pointed out in the journal Comprehensive Psychology , comparing the quality of same-sex parenting with "mixed-orientation" parenting may be much harder than anyone thought.
In a nutshell, the problem is this. The children of an intact biological family with a married mother and father grow up in circumstances which have been thoroughly studied by sociologists. Most importantly, from conception they have had only one father and only one mother. These families are complicated enough to give sociologist headaches. The quality of the couple's relationship, the number of children, the financial circumstances, the employment history, the health of children and parents, the place of residence, and so on and so on.
But the children of same-sex couples exist in a different framework altogether. They are not the natural progeny of a married couple. Rather, they have been "imported" into a relationship and they carry with them some of their past experiences.
Big problems of definition are a result. For instance, Schumm examines the limitations of studies based on the National Longitudinal Study of Adolescent Health (known as the Add Health study), a huge and very important dataset on which many studies have been based. Unfortunately, each study had its own definition of important variables, like "single parents", "stepfamilies", "lesbians" and so on. Most of them looked at what the structure was at the time of the interview rather than the history of the family. (This is one advantage of the data examined by Regnerus in the New Family Structures study.) So it is difficult to identify "same-sex parent families" from this data. As Schumm points out:
"In the Add Health data set, most studies have not assessed different structures among same-sex parent families, especially with respect to male same-sex parent families. Those that have categorized family structure indicate the same problem of criteria: Davis and Friel (2001) identified 260 lesbian mother families in the data set, but later researchers only identified between 18 (Patterson, 2009) and 44 (Wainright & Patterson, 2006) lesbian couple families."
It is difficult to say how big a "dose" of heterosexual parenting a child in a same-sex family received. In one well-known study of 28 children which supports "no difference" thesis, Schumm says, "children who had spent most of their life in heterosexual families were, in fact, included within the operational definition of children from lesbian families". One nine-year-old child who had only been with a lesbian couple for nine months was classified as belonging to a same-sex family.
How can researchers draw conclusions from data when family structures are changing over a the course of a child's lifetime? Schumm says that it requires very sophisticated interpretation of the data:
"The challenge for understanding research about LGBT parent families is that any interpretation of 'LGBT' must remain somewhat cautious if such families have been self-identified as heterosexual for longer than they have self-identified as non-heterosexual. To ascribe child outcomes to parental sexual orientation as a function of a strict binary typology (heterosexual vs gay or lesbian) based on the family's most current status would seem to overlook any sense of the relative duration of different types of family environments to which children had been exposed."
Schumm's study suggests that definitive proof of "no difference" thesis is still a long way off. If only the judges would listen.