Sara Watkins was two years old when her parents began taking her and her six-year old brother Sean to see a band called Bluegrass Etc. at a pizza parlor in their hometown of San Diego.

“There was this fiddle player in the band,” she told me recently, “and for some reason that was the instrument that spoke to me.”

By the time she was eight, she and her brother had a band called Nickel Creek, and they were performing at bluegrass festivals and competing in regional contests. Sixteen years later, they’ll be at the NorVa Sunday night in support of their third album, Why Should the Fire Die?

“It’s natural that it doesn’t sound exactly like the other two records,” she said of the new CD. “But the first two didn’t sound that much like each other either. The main agenda was to put something out that represented us live, something that had an authentic energy.”

It’s a natural energy born of the eclectic musical influences she and her brother have shared and explored through their adolescence and young adulthood, playing night after night with their longtime bandmate Chris Thile, whom they met at that same pizza place. Though only in their twenties, the trio has already been together longer than the lifetime of most bands.

“We are largely a brother/sister act,” Sara explained, “because Chris is pretty much like a brother. We stay involved in each other’s lives because we pretty much live together. If you live with anybody you’re going to get tired of them, and that happens, but we’re so close that it’s really nice to be able to get mad at each other and then ten minutes later, ‘OK, let’s get along.’

“It’s incredibly unique and something that we appreciate very much. Beyond musical, a band is very personal. We have friends who play in bands where the only reason the band is together is for the musical effects---that’s the only reason they know each other. We are fortunate. We’ve spent more than half of our lives together and had our primary experiences around each other, you know, going through the teenage years and things like that. Our families are very close, and that kind of personal connection is really valuable, especially when there are frustrations on the business side of things. We’re appreciative of what it means to have a deeper connection.

“We went through all of the stupid, but very real, issues that bands go through in figuring out how everybody fits, and what’s acceptable behavior and what is not. We hashed through a lot of stuff when we were too young to know that a band could break up. I was eight when the band started and so was Chris; Sean was twelve. Within four years we were dealing with really intense relationship issues, relationship in the truest sense. There were no romantic things happening---that’s terminal---but figuring out how to relate to each other, and going through big issues before you really understood. Fortunately, we did a lot of this stuff before we had a lot of pride or identity issues. You’re doing this when you’re fourteen or fifteen and you’re really confused about a lot of other stuff too…We’re pretty tight.”

Though they started out as a fairly straightforward bluegrass band, the trio’s music has evolved into a genre-bending, genre-blending amalgam that is fresh and invigorating. It remains rooted in the acoustic instrumentation the threesome favors---Chris on mandolin, Sean on guitar, Sara on fiddle (she won the Arizona State Fiddle Championship at age 15). Nickel Creek is in the forefront of the new acoustic movement---Yonder Mountain String Band, String Cheese Incident, Keller Williams---that has found a young audience eager for something real and less bombastic.

“I think it’s kind of a natural balancing act with all the electronics and huge productions that are happening,” Sara said. “There will always be an attraction to the beauty in actual instruments. Seeing somebody open a case and being able to actually make music out of it is just beautiful. It’s something that we all grew up with.

“It’s astounding to me how many young people have never seen an instrument come out of a case. They think that music comes out of a plastic stereo or an iPod or the radio; they have no concept of people practicing and trying to learn how to develop their craft. Being in the presence of that is undeniably attractive. The frailty, that things are imperfect, is the most lovely.”

Sara Watkins singing Bob Dylan’s “Tomorrow is a Long Time” is truly lovely too.

“When you’re around family members and people who you really trust,” she reflected, “you have this unspoken remembrance of who you are and what you should be doing.”

When you hear Sara and the boys cut loose on the Celtic rocker, “When in Rome,” harmonize on “Jealous of the Moon” and “Why Should the Fire Die?” or smoke through the virtuosic instrumentals, “Scotch and Chocolate” and “Stumptown,” you know they are doing exactly what they should be doing.