A recently published study by sociology professor Mark Regnerus purports to show that children of same-sex parents experience a significant degree of negative outcomes, contrary to numerous earlier studies on LGBT parenting. Most notably, the new study alleges that the children of lesbian mothers are more likely to be on public assistance, more likely to be unemployed, less likely to be employed full-time, more likely to be cohabitating, less likely to be married, more likely to have had an affair, more likely to have had an STI, more likely to have been in therapy recently, more likely to have recently thought about suicide, more likely to have been raped, and more likely to have been molested by an adult.

These findings would certainly be surprising – if they were supported by the evidence. While these results have been widely reported as representative of the parenting skills of same-sex parents, the study itself can tell us almost nothing about this. The shortcomings of its design make this impossible.

The study was conducted by surveying a representative sample of nearly 3,000 young adults aged 18 to 39, who were sorted into 8 categories of family structures: an intact biological family of a married mother and father, lesbian mothers, gay fathers, adoptive families, biological parents who divorced after their children were grown, stepfamilies, single parents, and all other kinds of families.

However, the groups designated as “lesbian mothers” and “gay fathers” are actually defined by whether one of the respondent’s biological parents ever had a same-sex relationship during the respondent’s childhood. Little information is given about the nature and duration of these relationships, and the set of people whose parents once had any kind of same-sex relationship is not identical to the set of people who were raised in a household with same-sex parents. Same-sex relationships aren’t limited to committed same-sex couples raising children. This definition could also encompass a same-sex affair outside of an opposite-sex marriage, a parent who services clients of the same sex in the course of sex work, or same-sex activity within the context of an open relationship. For the purposes of this study, these situations are all lumped in with committed same-sex partners raising children.

The labels of “lesbian mothers” or “gay fathers” also ignore the fact that having had at least one same-sex relationship does not necessarily make someone gay, any more than one opposite-sex relationship makes someone straight. In an article in Slate Magazine, Regnerus says, “our research team was less concerned with the complicated politics of sexual identity than with same-sex behavior.” But the study says nothing about the nature or extent of that behavior aside from whether it was ever present to the slightest degree, or completely absent as far as the respondents were aware.

What little data the study does provide in this area mostly pertains to the length of time the respondents spent in a household with same-sex partners, which turns out to be… not much. Of the respondents in the so-called “lesbian mothers” group, who numbered 163, only 57% reported living with their biological mother and her same-sex partner for at least 4 months, and 23% lived with them for at least 3 years. In the “gay fathers” group, numbering 73 people, 23% said they lived with their biological father and his same-sex partner for at least 4 months, and less than 2% lived with them for at least 3 years.

There are two flaws in comparing these respondents to those in the “intact biological families” group as a measure of the effects of same-sex parenting. First, this suggests that while the 18 years spent with one’s married heterosexual parents are responsible for these positive outcomes, the mere months that many respondents spent in a household with same-sex parents must be responsible for their negative outcomes. This completely ignores the effects of whatever other family structures they were a part of during the many years that they did not spend with their same-sex parents. And in the case of those who spent no time living with a parent’s same-sex partner, how could any of their outcomes possibly be attributed to same-sex parenting?

Second, Regnerus’ 8 categories of family structures are not mutually exclusive. A respondent with a parent who had at least one same-sex relationship could also have lived with their married biological parents for their entire childhood, or had a stepfamily, an adoptive family, a single parent, or some other kind of family. Regnerus acknowledges this, and states that he “forced their mutual exclusivity” for the sake of “maximizing the sample size” of the “lesbian mothers” and “gay fathers” groups. Unfortunately, this makes any comparison between the “intact biological families” group and either of the “gay” parent groups practically useless.

Regnerus has filtered the other six groups – biological parents, stepfamilies, adoptive families, later divorced parents, single parents, and all others – so that they consist only of parents who are believed to be exclusively heterosexual. But he’s constructed the two “gay” parent groups so that they consist of a hodgepodge of these family structures. Every other group contains only one type of family. The “gay” parent groups contain potentially all of them.

Regnerus’ treatment of these groups thus fails to separate the possible effects of having a stepfamily, a single parent, divorced parents, married biological parents, or being adopted, from the effects of a parent having at least one same-sex relationship. As a result, the outcomes that he attributes to same-sex parenting could just as well be due to family instability. He isn’t comparing married heterosexual parents whose children lived with them for 18 years to committed same-sex couples whose children lived with them for 18 years. He’s packed the “gay” groups with divorces, remarriages, adoptions and single parenthood, and then compared them to intact heterosexual families. Of course the results would reflect unfavorably on the groups he’s designated as gay. But they don’t tell us anything about the outcomes for children who were raised by committed same-sex parents for a substantial portion of their childhood.

Regnerus himself has admitted to these shortcomings, but claims that there was no way to overcome these limitations. On his blog, he wrote:

One of the key methodological criticisms circulating is that-basically-in a population-based sample, I haven’t really evaluated how the adult children of stably-intact coupled self-identified lesbians have fared. […] And I’m telling you that it cannot be feasibly accomplished. It is a methodological (practical) impossibility at present, for reasons I describe: they really didn’t exist in numbers that could be amply obtained *randomly*. It may well be a flaw-a limitation, I think-but it is unavoidable. We maxxed Knowledge Networks’ ability, and no firm is positioned to do better. It would have cost untold millions of dollars, and still may not generate the number of cases needed for statistical analyses.

Considering how many inaccurate stories about same-sex parents have been published because of what his study falsely claims to show, this is an especially weak excuse. If the data aren’t there, then the data just aren’t there. This doesn’t mean you can misrepresent committed same-sex parents by grouping them with all kinds of disrupted families and different living situations. It means your study simply isn’t capable of examining the competence of same-sex parents. And Regnerus should have admitted that in the first place.