Thank you for pointing that out. I was going by the date on some website, so I thought it was from 2012. The most recent ABA assessment is actually this 2015 amicus brief filed for the Obergefell case: http://www.apa.org/about/offices/ogc/amicus/obergefell-supreme-court.pdf There remains no clear evidence that children of two fathers or two mothers are disadvantaged relative to children with both a mother and a father, but there are some telling lines in the APA’s amicus brief.
On page 29, they state that “researchers must take care to avoid conflating the negative consequences of experiencing divorce or household instability with the consequences of simply having a gay or lesbian parent.” This is indeed an important distinction, but if same-sex relationships were less stable than opposite-sex relationships on average (the early evidence is mixed), should adoption agencies be able to take that into account?
On page 33, they acknowledge: “More research has focused on lesbian mothers than on gay fathers, but published studies of gay fathers find that they are as fit and able parents as heterosexual fathers.” This is a bit misleading, because whether gay fathers are as able parents as straight fathers was never the primary question. The question is whether two fathers are as able at parenting as a mother and a father (or two mothers).
One specific question I am interested in is whether children raised by same-sex parents are equally capable of sustaining stable opposite-sex marriages. My hunch that they might not be is based only on my personal experience of drawing on my own parents’ example in navigating my own opposite-sex marriage, but my main point is that we do not yet have the data to answer a question like this, since there are so few children of same sex parents who have reached middle age.
“A 2004 study of registered partnerships in Sweden reported that gay male couples were 50% more likely to divorce than were heterosexual couples. Lesbian couples were nearly three times more likely to divorce than were heterosexual couples.” http://blogs.wsj.com/ideas-market/2013/04/03/the-science-on-same-sex-marriage/tab/print/
“After controlling for marriage and marriage-like commitments, the break-up rate for same-sex couples is comparable to (and not statistically distinguishable from) the break-up rate for heterosexual couples.” http://web.stanford.edu/~mrosenfe/Rosenfeld_Couple_Longevity_Forthcoming_JMF.pdf)