There is nothing like the sound of siblings singing together.

Whether it’s the Beach Boys or the Everly Brothers—or, more recently, First Aid Kit—absorbing the same breathing rhythms and speech patterns adds an element to vocal harmonies that can be pure magic.

“It’s just second nature, like a fifth limb that’s already on you,” says oldest sister Natalie. “There’s an ability to anticipate what’s going to happen and blend with it. When Meegan and Allison sing, they know exactly what I’m going to do and when.”