The Public Discourse has a post about a new book that summarizes what we know so far.

Here is the introduction:

An important new collection of peer-reviewed scholarly papers entitled No Differences? How Children in Same-Sex Households Fare has just been released by the Witherspoon Institute. The papers included and summarized in the book all study the nexus between children’s well-being and the structure of the families in which they are raised. In particular, the authors focus on the efficacy of families in which the adults are involved in a physically intimate same-sex relationship.

Here are the chapters:

1. Loren Marks: survey existing studies on parenting by same-sex couples
2. Mark Regnerus: large-scale study comparing standard parenting vs same-sex couple parenting
3. Douglas Allen, Catherine Pakaluk, and Joseph Price: analysis of studies based on census data
4. Douglas Allen: study of educational outcomes of children raised by same-sex couples
5. Walter Schumm: evaluation of the methodology of the Regnerus study
6. Walter Schumm: analysis of the stability of standard relationships vs same-sex relationships

Here’s the blurb on one of the chapters:

The first paper included in the volume, by Loren Marks, examines the foundations of the position taken by the American Psychological Association (APA) on what it calls “lesbian and gay parenting.” The 2005 APA monograph setting forth that organization’s position asserts that the question of whether the childrearing efficacy of parents in same-sex relationships is at least the equal of that of heterosexual couples is settled, and that the serious academic literature speaks with a single voice on the matter.

Marks reviews an extensive literature on the topic and finds that most of the studies on the subject rely on “convenience samples”: groups of respondents that cannot be considered cross-sections of the population at large. Convenience samples are a staple of the literature because same-sex parenting is rare, and so recruiting same-sex parents for a study generally involves placing ads at day-care centers and in publications aimed at the LGBT population, or contacting people by way of their network of friends. While they can provide a useful window on the experience of parents in same-sex relationships, Marks notes that convenience samples suffer from two generic problems. First, the sample sizes are very small; one of the better studies might include a dozen or two lesbian families and a comparable number of heterosexual families. In such a small sample, only enormous differences in children’s outcomes will rise to the level of statistical significance. Technically speaking, estimates of the difference between outcomes for same-sex parents and those for heterosexual couples suffer from low “power.” Moreover, because convenience samples do not constitute a random cross-section of the population, they are not representative, and so estimates based on them suffer from a problem known to statisticians as “bias.”

Marks also notes that many of the small studies either fail to identify a comparison group of heterosexual parents, or they compare educated and affluent lesbian couples to single heterosexual parents. He suggests that better comparison groups might consist of married heterosexual parents or of all heterosexual parents. Certainly that would be the case if one wanted to maintain that there was no difference between the status quo outcomes for children of parents in same-sex relationships and those of heterosexual married parents, as some have seemed to want to do.

Marks highlights three studies that avoid small convenience samples and work with much larger random samples, two of which can be found in the new volume, in the chapter by Mark Regnerus and the chapter by Douglas Allen, Catherine Pakaluk, and Joseph Price.

I took a quick look at Loren Marks’ bio:

Loren Marks holds the Kathryn Norwood and Claude Fussell Alumni Professorship in the LSU College of Human Sciences and Education where he teaches family studies classes and conducts research on family relationships. He currently serves as Program Director for Child and Family Studies in Louisiana State University’s School of Social Work. Marks received his B.S. and M.S. degrees from BYU, and his Ph.D. from the University of Delaware.  Since beginning his work at LSU in 2002, Dr. Marks has centered his research efforts on religion and families, and has published more than 70 articles or chapters, as well as the book Sacred Matters (with Wes Burr and Randy Day). He has also studied children’s outcomes in various family forms—and strong African American families.  His research has received national media attention from outlets including The New York Times, The Washington Times, The Boston Globe, and The Wall Street Journal. Loren was honored with college-level teaching awards in 2005, 2009, and 2013.  In 2011-2012, LSU nominated him for the national Carnegie (CASE) Professor of the Year Award—and nominated him again in 2014. He is Co-Director (with Dr. David Dollahite) of the American Families of Faith Project that includes about 200 Christian, Jewish, and Muslim families from all eight regions of the United States. Findings from this ongoing project have resulted in over 50 scholarly articles/chapters and two in progress books.

The Kindle edition of the book is currently $7.99. The volume is basically one stop shopping for this issue, so if you ever debate on this, get the book.

The best philosophical book on the definition of marriage is “What is Marriage?” by Girgis, Anderson and George.

I think if you are interested in same-sex marriage as a policy issue, you should get both of these books first.