It’s difficult to unearth the truth with all the noise and fanfare surrounding the studies that purport to show “no difference” between children raised in the home of same-sex parents and those raised in the home of their married mother and father. It’s also discouraging that in our highly educated, scientifically minded society many have accepted this claim without really understanding the evidence. So, if you are a fan of data and research, here is an itemized review of every single study done on the subject of same-sex parenting: A Review and Critique of Research on Same-Sex Parenting and Adoption. For those who don’t have the time to review this 120 page document, here’s the abstract:

Are the outcomes for children of gay, lesbian, or bisexual parents in general the same as those for heterosexual parents? That controversial question is discussed here in a detailed review of the social science literature in three parts:

(1) stability of same-sex parental relationships,

(2) child outcomes, and

(3) child outcomes in same-sex adoption.

Relationship instability appears to be higher among gay and lesbian parent couples and may be a key mediating factor influencing outcomes for children…

Studies conducted within the past 10 years that compared child outcomes for children of same-sex and heterosexual adoptive parents were reviewed. Numerous methodological limitations were identified that make it very difficult to make an accurate assessment of the effect of parental sexual orientation across adoptive families…

There remains a need for high-quality research on same-sex families, especially families with gay fathers and with lower income.

In short: the studies that show “no difference” often used poor methodology (non-random samples, parental (self) reporting vs. actual child outcomes, short duration, etc.) to reach their conclusions.

This may explain why those “no difference” outcomes were so prevalent in the early same-sex parenting studies:

First, the participants were aware that the purpose was to investigate same-sex parenting and may have biased their responses in order to produce the desired result.

Second, participants were recruited through networks of friends or through advocacy organizations, resulting in a sample of same-sex parents of higher socioeconomic status than is typical of parents in a same-sex relationship generally.

Third, on average, samples of fewer than 40 children of parents in a same-sex relationship virtually guaranteed findings of no statistically significant differences between groups.

In other words, researchers would sometimes recruit subjects via posts on an LGBT-friendly site, state that they were doing a study on gay parenting, and then hand select 20-40 participants. (Not exactly the unbiased scientific method that you learned about in high school.)

In any field of study, such factors have a major impact. But when you take into account the cultural/political landscape leading up to redefining marriage, it’s clear that something other than scientific inquiry played a role in the outcomes. One analysis revealed that:

studies which recruited samples of children in same-sex unions showed that 79.3 percent (range: 75–83) of comparisons were favorable to children with same-sex parents. In comparison, there were no favorable comparisons (0%, range 0–0) in studies that used random sampling. The evidence suggested strong bias resulting in false positive outcomes for parent-reported measures in recruited samples of same-sex parents.