Kim Forester once explained part of the magic of sibling musical acts: "We share the same facial structure and the way the tone resonates within the head," she said. "And there's an instinct, an intuition about each other, coming from a whole lifetime together."

But whether the harmonies come from bone structure or similarity of voice quality or even from a shared background and tastes, the Forester Sisters have joined a long and distinguished line of sibling ensembles, including the Bellamy Brothers, the Everly Brothers, the Andrews Sisters. The list could go on. And one thing they all seem to have is an incredible harmony.At the Westerner Sunday night, their four voices blended as smoothly as honey and butter. And while they listened enthusiastically, people laughed and clapped along, moved around the dance floor and generally had a great time.

The quartet, named the Academy of Country Music's "Best Vocal Group" in 1987, didn't stick solely to contemporary releases. They instead crossed a lot of years to provide a sampling that included the '50s-ish "Sincerely" (reminiscent of the Andrews Sisters) and "Oh Lonesome Me," once popularized by Johnny Cash.

They also showcased songs that are becoming very familiar to anyone who listens to radio stations that play country music, like "Lyin' in His Arms Again" and "I Fell in Love Again Last Night."

Along the way, they traded off on singing the leads, so that each performer was showcased a number of times. And they changed the pace often enough to keep the audience enthralled, switching from almost-ballads to toe-tapping, hand-clapping numbers that had everyone moving.

But the audience seemed happiest when the sisters - Kathy, June, Christy and Kim - slowed things down a little with love songs like "I'd Choose You Again," "Tears After Years After You" and "Letters Home."

It's refreshing to see a successful group that maintains a kind of down-home quality, and the Forester Sisters do. They provide a smooth show, but it doesn't feel "slick" - although some of the choreography is a bit mechanical and unnecessary. I have a suspicion the women have practiced their introductions to the songs, but they managed to make them sound off-the-cuff and entertaining.

The Westerner's an interesting venue for a concert. The capacity's close to 1,000, seated at small tables, and there are couples out on the dance floor throughout the show. Yet, unlike arenas and concert halls, there's a feeling of intimacy. You can chat with your friends without disturbing others; you can move around and stretch.

And you can hear some first-rate music. We did Sunday night.