Back in the mid-1970s, Marian Mitchell was a single mother, a recent divorcee who emerged from the closet only on Saturday nights, heading down to Sneakers, a women's bar at Second and Market.

Once, Mitchell's daughter, then 9, asked, "Why don't you date boys?"

"Because Mommy likes girls," was the reply.

A generation later, Mitchell found herself fielding a new round of questions. "Mom-mom, what does LGBT mean?" her oldest granddaughter asked after seeing the acronym for lesbian/gay/bisexual/transgendered on a sign in Mitchell's kitchen.

But Mitchell no longer keeps her identity cloaked. After her longtime partner died in 1997, Mitchell decided it was time to come out. To everyone - including her grandchildren.

Mitchell, 55, coordinates the calendar for Amazon Country, a women's-music show on WXPN. Each month, members of the Lesbian Group of Montgomery County fill her Juniata living room for Rocky Horror theme parties or competitive puzzle-making nights. Her grandkids - 19-year-old Kimberly, 15-year-old Kayla, and 10-year-old Chaly - almost always join the festivities.

"When I was closeted, it was like living a double life," Mitchell said. "I never imagined being able to live so openly. It's so much easier to just be me."

"Lesbian grandmother" or "gay grandpa" used to sound like a contradiction in terms. But now gay grandfolk are a quietly emerging demographic - men and women who married in the 1960s and '70s, had children, and came out later, sometimes only after their children were grown.

There's still no grandparent equivalent of the children's picture book Heather Has Two Mommies. But a recent novel, Grampa Jack, chronicles a gay grandfather's fight for custody of his 6-year-old grandson. And an online boutique sells kids' T-shirts emblazoned with the words "I love my. . .trailblazing. . .woman-loving. . .out and proud grandma."

"There is a growing number of gay grandparents who are looking for ways to explain to their grandchildren who they are and who they love," said Jennifer Chrisler, executive director of the Family Equality Council.

Even the youngest gay and lesbian grandparents, those in their early 50s, can remember the Stonewall riots that kick-started the gay civil rights movement in 1969. In 40 years, the world has changed. And so have they.

Marian Mitchell knew she was different as far back as third grade, when she had fierce crushes on female teachers and other girls. But that was the 1960s. She didn't dare speak the L-word.

It's different now. Mitchell's granddaughters spent time with her partner, Chris Saloma. "When I tell my friends my grandmother's a lesbian, they say, 'Really? She is?' They're cool about it," Kim said.

So is Kim's mother, Angela Bennett - though she does remember a brief period of discomfort about Mitchell's sexual orientation. As a teenager, she was afraid to openly admire another girl - even to say her jeans looked nice - because someone might think that she, too, was a lesbian.

Mitchell recalled watching television with Saloma 20 years ago, before Kim was born. "The only place you saw lesbians on TV then was on the talk shows, and they looked like they were scraped from the bottom of the barrel. We both said that we were going to make sure my grandchildren would see that there are many good people out there who happen to be gay or lesbian."

Larry Buss and Roy Wilbur arrived at the Bryn Mawr Birth Center early on a Saturday morning last May, a brand-new Gund teddy bear in hand. Another set of grandparents - the usual male/female variety - showed up at the same time.

"I looked at them and said, 'You're undoubtedly the grandparents,' " Buss said. "They looked at me and I said, 'We are, too.' "

Now, eight months later, a picture of Sonja, Buss' first grandchild, fills the screen of his computer at Drexel University College of Medicine, where he manages budgets for the Office of Educational Affairs.

"She is the most supremely adorable, talented, wonderful child," he gushed, adding, "I was predestined to be a grandfather."

Thirty years ago, he might have said otherwise. Buss left his marriage and came out in 1980, when his daughter was 7 and his son was 2. "I grew up in a generation that still felt tensions about identifying themselves," he said.

After meeting Wilbur, an arts consultant, the two settled into a life Buss now describes as "typically gay" - vacations in Provincetown or Miami, volunteer stints with Philadelphia Community Health Alternatives, evenings in the "gayborhood" of Center City.

But every other weekend, they were just "Dad" and "Roy" - taking the kids to the Franklin Institute, the zoo, the Art Museum, the Lehigh Gorge hiking trails both men loved. As the kids grew older, they joked that Wilbur, now 51, was their "step-other."

These days, Buss, 63, savors nothing more than a 90-minute babysitting stint with his granddaughter.

"I think Roy and I can serve as a model of a happy relationship," he said. "I think she'll grow up with us as the norm. I want to convey the idea that it's better to be extraordinary than normal, and to follow your bliss."

That outlook may be one gift LGBT grandparents bring to the children in their lives, said Chrisler of the Family Equality Council. "Gay grandparents have a wisdom about how the world can change, and how people's prejudices can be moved over time. They've seen the long arc of history."

"People with LGBT grandparents learn a broader view of how people can love," says Beth Teper, executive director of Children of Lesbians and Gays Everywhere (COLAGE).

That is, if the grandfolk are out. Nancy Orel, a Bowling Green State University professor who interviewed lesbian and bisexual grandmothers for a 2006 journal article, found that some grandmothers feared that coming out would rupture the relationship with their grandchildren. Others had explicit direction from their adult children to keep the "lesbian issue" under wraps.

"Those who were not out felt a lot of anxiety; they felt shame that they were keeping such a large part of their identity a secret," Orel said.