The study published by Professor Mark Regnerus this week certainly has some flaws, and many of the comments made about it have some merit. However, as a matter of intellectual honesty, it needs to be recognized that virtually all the studies of
same-sex parenting that have been conducted thus far fall far short of any standard of scientific testing.
Of the 50-plus such studies done in the past 15 years, the vast majority come to the same conclusion:
Children of gay parents perform at least as well as children from heterosexual families; there is no difference in child outcomes based on family structure. (insert your favorite conclusion about raising children here.)
For several reasons, this literature is unlike anything else within social science. First, it partly arose from, and was strongly influenced by, legal cases
in which lesbian mothers were denied custody of their children on the basis of their sexual orientation. Second, for the most part it has been written by individuals with strong personal worldviews who sympathize with those studied. Third, the focus of the literature is often on “soft” measures of child and family performance that are not easily verifiable by third-party replication , and that differ substantially from measures used in other family studies. One of the odd characteristics of this literature is the lack of consistency of measures across time. Subsequent studies seldom test for measures that were used in previous studies. Fourth, the data and procedures used in the studies are never made available online in order for other scholars to replicate findings. And finally, almost all the literature on gay parenting is based on weak designs, biased samples, and low-powered tests.
The result is a nascent literature that falls far short of standard social-science research. At its best, the literature contains interesting exploratory studies that raise provocative questions and make interesting observations. At its worst, it is advocacy aimed at legislators and judges — which may explain why, despite its weak scientific nature, the literature is characterized by strong recommendations for policy and legal changes to family regulations.
Yep, sounds about right. Bottom line is, basically all the research into the effects of any parenting technique at all whatsoever has been awful. See also this book