WASHINGTON — The modern-day Trapp family singers were hanging out on the craggy patio of a D.C. cafe, each wearing some variation on skinny jeans, bangs and combat boots.

Melanie, 25, had wrapped herself in a leopard-print trench, while Sofi, 27, was clad in a cropped red leather jacket. Amanda, 24, was in head-to-toe black. And then there was August, just 21, who let his hair do all the statement-making, the bleached-blond wisps of his bangs swooping over one eye, Bieber-style.

“What,” Amanda asked wryly. “You were expecting lederhosen?”

Well, uh, yeah. But could you blame us?

The musical foursome known as the von Trapps is the spawn of the wholesome, singing Austrian clan of “The Sound of Music” fame. Their grandfather, Werner, was one of those von Trapps, who skipped around the world in the 1930s and ’40s as the Trapp Family Singers, belting out madrigals and the folk songs of their native Austria for audiences shell-shocked by successive wars.

The older generation of singing von Trapps became the very loose source material for a Rodgers & Hammerstein Broadway musical, and then for one of the most-watched movies of all time, an epic that could give a Bollywood movie a run for its money with its romance, musical numbers, Alpine scenery and Nazi bad guys.

But just as Miley Cyrus declined to follow dad Billy Ray’s path into country music, the siblings Melanie, Sofi, Amanda and August are leaving behind the Austrian lullabies for something unexpected.

The von Trapps moved to Portland, Oregon, to forge careers as indi -rockers. Ask them who they want to sound like, and they’ll tick off names such as Fleet Foxes, Beach House and Sufjan Stevens.

In April, the von Trapps lobbed their first EP of original music, “Dancing in Gold,” out into the universe, where EPs are generally greeted like cosmic space junk.

Unless, of course, your name is von Trapp.

In that case, four songs were enough to prompt a call from their agent wondering how they’d feel about maybe opening for Loretta Lynn in Washington.

So here they were, sipping coffee before load-in at the Lincoln Theatre, where the great-grandchildren of the Captain and Maria von Trapp would share a bill with the coal miner’s daughter.

After immigrating to the United States in 1939, the Captain, Maria and the first generation of singing von Trapps settled in Stowe, a hilltop town in Vermont. They bought a farm and opened a ski resort, the Trapp Family Lodge. They pursued other passions.

By the time Maria’s memoir was adapted into the 1959 Broadway musical, and the fair-haired, porcelain-skinned Julie Andrews was cast as the dark-featured matriarch a couple of years after that, the Trapp Family Singers had abandoned gigs for good. The von Trapps scattered, landing all over the country.

So Stefan von Trapp, Werner’s son, and his wife, Annie, didn’t have much interest in music, the kids say. “Our parents had no clue what it was to go on tour or have kids in the music industry,” August said.

It was dairy farmer Werner (the one who was re-envisioned as the blond, chubby-cheeked “Kurt” for the silver screen) who taught his grandchildren to sing on his visits to the family home in Montana. Stefan and Annie indulged them and ferried them to vocal lessons after that, the kids say. That the couple took the children all to a single lesson, together, proved fateful: The young von Trapps became harmonizers, kinda like the old von Trapps.

And, of course, they already had the name.

Doors open for von Trapps. We root for them. They make us feel fuzzy inside, not like those wayward Partridges.

IN 2001, THE VON TRAPPS were invited to sing at Ground Zero for firefighters on their lunch breaks. It was the first time they’d left Montana for a gig. August was just 7, but soon, they were getting requests from all over the world. (Stefan and Annie declined requests for an interview but sent a statement that read, in part, “We believe that by touring the world since they were young, it gave them an education that helped them understand, appreciate and love people – they’ve become unique and very wise. We are so proud of them and the music they produce.”)

These days, they’ve been taken under the wings of the modern orchestral act Pink Martini, and produced “Dancing in Gold,” with Israel Nebeker of the Portland band Blind Pilot. Sometimes, Rufus Wainwright – sired by another renowned musical family – would show up while they were recording.

They’ve booked a three-night stand at the John F. Kennedy Center for the Performing Arts this December.

At the Lincoln Theatre, where the four performers stood at their mikes and harmonized through a sparkly, if spare, 25-minute set, it wasn’t until Melanie announced that they were the von Trapps that the audience began to shift in its seats and murmur.

Of those von Trapps?

When they were done, a few in the audience even rose to give them a standing ovation.

If the name opens doors, it can also bury the von Trapps under expectations.

“There are times when it has that nice ring of fate to it,” August says. “But we’re not trying to do what they did already.”

Among their sprawling clan these days, in fact, no one else seems to want to inherit the family business. The von Trapps have one aunt in music, and so far, they’re the only ones who have wanted to use the name for their own musical group.

Sometimes, even the von Trapps haven’t wanted it. “We definitely toyed with the idea of going with an underground name, like the Trappezoids or something,” Amanda says with a laugh. “It takes people a long time to get that our art is a little bit different than what they’re expecting.”

THE VON TRAPPS are hoping they’ll be recognized for “Dancing in Gold,” the first of three EPs they plan to release in the coming years, each with a different producer. On it, they evoke the Carpenters as well as She & Him, Zooey Deschanel’s AM radio homage act with M. Ward.

“There’s a whole generation of people for whom it was an annual event to tune into ‘The Sound of Music,’ ” says Thomas Lauderdale, founder of Pink Martini, who jokes that he is “both a mentor and cautionary tale” for the von Trapps. He recalls that even he was “very curious to see what this new generation was like.” They were everything, he says, you hope the von Trapps would be. “They are navigating that as well as anybody could,” Lauderdale says.

One way is by embracing their legacy, the real one and the celluloid one.

At the Lincoln Theatre, they left the audience with one last song, which, Sofi announced with an expectant smile, was about a flower that grows in the Alps.

It was “Edelweiss.” And though the von Trapp elders never actually performed it – like “Do-Re-Mi,” it was pure musical fiction, written for the Broadway show – their hipster descendents didn’t mind indulging the fantasy a bit.

“We are von Trapps,” Sofi said. “It is our last name, and we want to celebrate what our grandparents did.”

“But,” added Melanie, “we are who we are.”