the best way to tell is to ask. I had breeders tell me they don't know. not the answer I was looking for, but at least it was honest. and the pastel was very nice. so you can get nice pastels without knowing the line. but, if you want a certain line, then you need to find a breeder who didn't dirty up the line. select breeding is what this is all about, and with pastels, it really shows when you see in an ad lemon pastels, and it doesn't look much better than one of my normals.