Historically, same-sex couples lived on the fringes of American society and never thought they could aspire to marital rights. All that changed after the Stonewall Uprising, the 1969 police raid of Greenwich Village's Stonewall Inn and the six-day violent street protests that followed.
Before that, gay couples "organized themselves along heterosexual gender lines," according to New York City psychiatrist Jack Drescher. "In a lesbian couple, one would be more masculine-looking and the other more feminine-looking, and they would kind of use the larger cultural ideas about how that would go."
Drescher wrote about the evolution of same-sex family life in his 2004 book, "Uncoupling Convention."
"Gay couples talked about their struggles that emerged out of not having clear gender guidelines," said Drescher. "For example, in heterosexual couples, if a man earns more money than the woman, that's OK. That's the way it's supposed to be. We know when that's not case, it can create problems."
Same-sex couples who "never had a problem beforehand" also struggled with income disparities. "Who is the woman and who is the man?" he said. "It didn't come up until they settled into their roles."
But today, in both heterosexual and homosexual relationships, there is a "blurring of the boundaries," he said. Men are increasingly taking on childrearing responsibilities that were once delegated to women.
When gay couples marry in the states were it is legal -- Connecticut, Vermont, Iowa, Massachusetts, New Hampshire, District of Columbia and now New York -- they have more choices, calling themselves, "wife and wife" or "husband and husband," or the neutral term, "spouse."
But even Drescher, 59, who is in a legal domestic partnership, is sometimes surprised.
"I hear of people referring to themselves as husbands and wives, and even though I am gay myself it's something that startles me," he said. "I grew up in a culture where things have different meanings."
As an illustration of the complexities of gender roles, Drescher cited the story of Thomas Beatie, the so-called "pregnant man" who gave birth to a girl in Bend, Ore., in 2008. He insisted that he be listed as the father on the child's birth certificate.
Beatie was born a woman, but legally changed his gender from female to male, surgically removing his breasts, but not his sex organs.
"The delivery room nurse said he had to be listed as the mother and wrote it on the form," said Drescher. "He was unhappy and went to the state to get it changed. They said he could be listed as the parent in gender-neutral language, but he kept insisting he wanted to be listed as the father."
Drescher said he grew "extremely annoyed" with Beatie, "and I didn't know why."
"I had some empathy for people on the religious right who don't like the notion of defining marriage," he said. "I had one idea of what it means to be a father. His idea was bumping up against my idea."
Drescher said most Americans are not used to seeing two grooms or two brides on a wedding cake.
"The cartoonists visually get it," he said. "But something in the way we use language strikes people as strange and they are not used to it."
"Culture can be both comforting and oppressive," he said of traditional roles.
As a society, both sexes are moving past the gender stereotypes as a majority of married women help support their families and more men stay at home and nurture children.
"In the early psychiatric literature, one of the early critics of homosexuality was a major theorizer about homosexuality as an illness, like a lot of 20th century thinking," said Drescher. "He asked, 'Why do couples act if they are a man and a woman if they are not trying to imitate heterosexual life?"
Instead, in both gays and straights, gender roles overlap.
Drescher's partner of 29 years is an architect.
"He fixes everything around the house, but neither of us feels any stereotypes," he said. "I am not interested in what the house looks like. My personality is all about books and scholarship. Our home is decorated based on how he decides, but I have veto power."