In her younger days, as she was starting to write and sing her own songs, Raina Mullen was obsessed with the sort of folk-pop hitting the charts from Laura Marling, Colbie Caillat and Ed Sheeran. In 2011, when she was a senior at Lyme-Old Lyme High School, Mullen even debuted a confessional acoustic tune, "Foolish Girl," on The Day's "Song Spinner" series.

At the same time, her older sister, Lindsay, was immersed in the music and lifestyle of the jam band scene — which basically shocked Raina. "Oh, my God, you're a hippie, Lindsay!" Mullen remembers saying. "You're a Deadhead!"

Raina Mullen — now 23 and a vocalist/rhythm guitarist in American Babies, a nationally touring act deeply rooted in the jam and roots band circuit basically invented by the Grateful Dead — laughs as she recalls her initial reaction to her sibling's musical tastes.

"At that point, bands like the Dead held no interest for me at all. I completely judged the whole scene without even listening," she says.

Mullen is calling from the American Babies van, where she's riding shotgun as the group heads to their home base of Philadelphia and a gig with the Disco Biscuits at the Fillmore. As part of the jam circuit, where acts build their followings through spontaneous and virtuosic performances within the loose fraternal parameters of like-minded bands, American Babies tour at a frenetic pace. They'll be in Bridgeport Friday at The Acoustic and in Providence Saturday for a show at Alchemy.

Mullen is the youngest member of the band, which is fronted by singer/songswriter/guitarist Tom Hamilton, who founded the American Babies in 2007. The lineup also includes guitarist Justin Mazer, bassist Mark Sosnoskie and drummer Al Smith. Their latest album, "An Epic Battle Between Light and Dark," came out last year and is a fine realization of Hamilton's creative vision — a hooky fusion of guitar-based classic and alt rock with psychedelic seasonings, easy-breeze melodies and plenty of breathing room for exploration. It's a sonic formula that, over the years, has earned them performances with artists like Phil Lesh, Bruce Hornsby and the Felice Brothers as well as at such festivals as Bonnaroo, Gathering of the Vibes, Electric Forest and the Cayamo Cruise.

That Mullen is in the group at all is a happy accident and one she never remotely anticipated.

An Old Lyme native, she grew up absorbing music from her father, Jeff Mullen, who owned the late Bank Street Café, a longtime mainstay in the local live bands scene. He also lovingly oversees the arcade and amusement rides at Ocean Beach Park.

"I'd definitely say my interest in singing and music came from my dad," Mullen says. "As a kid, we'd spend every Monday at the Ocean Beach car show listening to the oldies songs (that blared from the park speakers). That's all he would listen to in the car, too. At the time, it was 100.9 FM — 'good times, great oldies.' He would always sing along, and he's got a great voice. And he always encouraged me to keep singing and performing."

That was Raina Mullen's goal when she attended Manhattanville College in Purchase, N.Y., and studied in the music business and management program. To help defray college costs, she got a job in hospitality at the Capitol Theater in nearby Port Chester, a highly regarded entertainment venue that routinely hosts an eclectic calendar of top flight bands. It was there that Mullen met Hamilton, who was playing in Joe Russo's Almost Dead, a Grateful Dead tribute band that, at the time, featured Dead bassist Phil Lesh.

"Tom and I met backstage and started talking about Bob Dylan, and he was so knowledgeable and nice," Mullen says. "I told him I was writing songs, and he showed genuine interest."

At that point, Mullen was working on a series of recordings that would eventually come out on an EP called "I Dare You." The material is well-crafted contemporary pop in the vein of her earlier ambitions. But the finished mixes and arrangements of the tunes have a sophisticated studio sheen, in large part because Hamilton heard Mullen's original demos and suggested she come to his Lorelei Studios in Philadelphia. He offered to co-produce what was going to be a full-length album.

"He wasn't attempting to hit on me," Mullen laughs. "But I had already planned to record in Philadelphia anyway, and Tom has such a great studio and a great ear that we ended up recording there."

As they worked, though, two things happened. Mullen and Hamilton fell in love, and she also very much got into the music of American Babies — and, by extension, the whole jam band community. Eventually, she was offered the gig in American Babies, and the original plan — to finish and release her album and in the meantime continue at the Capitol Theater — changed.

"I love the Capitol," Mullen says. "It was a great job, it paid well, and the people who worked there and the bands that come through are still like family. But, after Tom and I fell in love, I moved with him to Philly and ended up in American Babies."

Having come to the "jam scene" relatively late, Mullen says her time in the group has been like a year-and-a-half long musical vacation.

"I've learned so much about music, and there's so much more to listen to," she says. "My influences have changed significantly, and the stuff I've been writing is completely different than what I was doing when I met Tom. I might still have a really poppy chorus, but the chord structures vary, and I love all the directions a song could go."

In that context, Mullen decided to release "I Dare You" as the shorter EP through her rainamullen.com website. She's proud of the effort but is focused on playing in and learning from American Babies. Onstage each night, she plays acoustic guitar, and she sings harmonies and occasionally some lead vocals. Her goal is to provide a few tunes on the band's next studio album.

"I had to learn a lot really quickly, and the first few months were really overwhelming," Mullen says. "I'd never even jammed with anyone before, let alone improvise segments on the fly onstage. To be honest, there aren't many women in the jam band world, but the guys in American Babies have been wonderful, and for the most part, I've been treated very well everywhere we go."

Mullen says she knows her dad worries about her but tries to reassure him.

"The road can be a rough place, and there are plenty of party scenes, but I barely even drink," she says. "There's too much to learn out here, and I don't want to miss any opportunity. Dad knows I've got a degree and a back-up plan, which is totally logical. But he's also supportive and knows this is what I always wanted to do. I think about that a lot. I've been so lucky to have gone from playing open mic nights at campus coffee shops to touring the country and meeting famous musicians every night. It's an amazing experience." She laughs. "Now I just have to embrace as much as I can and steal everyone's tricks!"