THIS!!! ^^^^ It's not always just the dog's lines. There are sooo many different aspects that make up a good agility dog that is it difficult to breed for that. Not just temperament, there is drive, precision, biddability, physical soundness, mental soundness, structure, and speed to name just a few. We all know that you can get a shy dog from outgoing parents, it happens, there is always variance in temperaments within a litter and a line does not make or break a good agility dog.