"Men and women make unique, irreplaceable, contributions to parenting. Both genders are needed for human flourishing."With it being more of a PR liability for anti-gay organizations to be more explicitly homophobic, NOM has taken this more subtle gender-based approach for opposing equality.
The New Jersey-headquartered NOM's thesis rests in that mythical notion that men and women are complementary beings, with each spouse in a man-woman duo providing something the other lacks, by sheer virtue of their gender alone, thereby creating a sum that's somehow greater than the whole of its parts. So to speak.
The argument is that same-sex couples are inferior to man-woman couples not because of sexual orientation, but because of their gender composition. NOM does not articulate, of course, what all of these "unique, irreplaceable, contributions to parenting" a woman makes that a man cannot, and that a man makes that a woman cannot.
I'm sure I'm not alone, however, in being super interested in seeing such a list should NOM ever take the time to think beyond soundbite-level and make those gender-based "contributions" available to the public.
In my experience, when gender traditionalists answer this question, their answers are absurd and make me think their circle of actual men and women they know must be like 5 people who are exactly like themselves. They will say things like, "Dads do rough and tumble stuff with their kids," as though no woman on Earth does or is even capable of such things! Or they rely on weasel-words like, "Women tend to" - as though if women as a group do one thing less than men as a group do, then no individual woman ever in the world does that thing. It's just such sloppy thinking that it seems almost like willful ignorance in service of privilege.
In fact, I reckon the details to NOM's gender soundbites don't matter much to the group's core supporters who are looking for that nice, civil, gender stereotype-y reason to oppose equality for a group it used to be much more popular to overtly hate and ridicule.
Doug Allen Study on Children of Same-Sex Couples
Same-Sex Marriage, Feminism, and Women