Now that I think of it, she shoots a bow right-handed, too.
Well, the bow is less about your dominant hand and more about your dominant eye, which isn't always on the same side. Basically, your eyes working together "center" your vision between them, but they will base that centering more on one eye than the other. If you point at a distant object with both eyes open, and then close one eye without moving your finger, your finger should appear to move away from the object. If it doesn't, then the eye that's still open is your dominant eye, and is the side you should be using to aim.
My husband is the only person I've ever met who can aim equally well with either eye.