Earlier, I referenced Same-Sex Marriage: The Legal and Psychological Evolution in America, a short collection (160 pages plus notes etc.) of essays on the topics by experts in the field. This volume was written a decade after William N Eskridge's still valuable "case" in 1996. The more recent volume provides more up to date case law, two chapters of somewhat tedious summary of psychological data, and a useful chapter on the development of state privacy law.
The psychological data is tedious in part because it basically reads like the abstract form of various studies, studies that bottom line (putting aside the somewhat limited data, especially as to gay fathers) say that there really is not much of a difference between same sex and heterosexual parenting.* The children of homosexuals might have to deal with some more prejudice, but the same is the case of the children of various disfavored heterosexual groups. Likewise, any number of the myriad of forms of parenting these days (single parent, divorced, et. al.) are as likely to affect children. Ditto various problem cases outside of sexuality itself.
Any difference tends to be positive, such as some children of lesbian parents being more open-minded, open about their emotions, and (for girls at least) more willing to experiment with same sex relationships. Child molestation is not a problem either, both given nearly no molesters are women of any sexuality, and most are heterosexual males. This underlines (in a useful chapter) why state courts (putting aside the special case of Florida) generally did not consider homosexuality itself a barrier to custody or adoption, though it might be seen in a negative light in various cases.
The book starts off with a quick summary of sexual privacy cases, listing the usual suspects from Griswold on, but lacking in not providing a more complete summary that could have equally been done in a few pages. The chapter on the "evolution of state law toward sexual privacy" provides a very useful reminder that the evolution is not just "the work of 'a few activist judges.'" [State constitutional traditions overall deserve more attention that they generally receive.] The reminder, from someone who was there, of the bad old days of divorce law underlines the point.
We also get a summary of the last few decades of the law of marriage in this country [Eskridge provides a more complete look at all the aspects here, including those in debt or in prison] and internationally. It is striking how much changed, even since Eskridge wrote his volume. One chapter provides an extended look at the many state and federal legal privileges that married couples receive. The chapter would have benefited from a bit more discussion on the obligations as well, suggested by a discussion of a possible divorce case where a husband leaving his spouse for another would have various responsibilities.
The mostly all business (with some comments here and there pointing out the sentiments of the authors) ended with a heartfelt message promoting extending freedom of marriage to same-sex couples:
Isn't it fair to do so?
Isn't it fair to do so now?
Of course it is.
Of course it is.
The book underlines it is not just fair but pragmatically useful. The ability of homosexuals in Florida to adopt has inhibited some to do so even after they were long term foster caregivers to special needs children. David Brooks was cited too; that often criticized conservative in effect thinks homosexuals should have the duty to marry since marriage brings forth various benefits to society as a whole. [I talked about the op-ed here.] Marriage is both a freedom and a responsibility, as many things tend to be. Prejudice does not just burden those who wish to marry, but society as a whole.
It tends to do that a lot.
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* This applies to sex roles as well, even if the parent(s) themselves try to be more sexually neutral about things. It highlights the important biological and societal drives here, though more liberal attitudes appears to affect things somewhat. Still, as noted above, even if some girls experiment more, actual lesbian behavior in the long term is not much different even here. OTOH, given biological connections, it should be somewhat if the biological parent is homosexual.
One interesting aspect is that there is a tendency for the children to differentiate between lesbian couples when it comes to parenting, the "social" mother (non-biological) often taking stereotypically paternal roles such as rough & tumble play. Or, at the very least, there is a clear division of roles played by each parent. It would be interesting to know how far this is a result of natural affinity, negotiation given the situation of the couple, or influenced by societal norms. But, either way, in a fashion, even same sex couples are not just "two peas in a pod" so to speak.
Something comparable might be the case for gay couples / boys, though the research is thinner and experimenting for boys is seen in a more negative light. The different roles lesbian mothers play might also be the best of both worlds, since even the non-biological or more "feminine" party overall appear to know more about parenting overall than even heterosexual fathers. Of course, all of these are just rough median descriptions, and people tend to come in various shades.