Now that's why i call any pure breed not an EE. I know there are project birds that they are working on getting them to breed true over and over to get them a standard and those once they breed true and blue eggs wouldn't be ee's any more but a different color of what ever breed they are trying to get the color added to that standard.
Now what i find weird is that you can have two colors that breed true but you cross them and they no longer breed true and become ee's. Like mixing silver ameraucana and a bbs one the off spring wont breed true from what I'm told. I've yet to try cause my silver girl aint laying yet. So this i will be testing.
They will breed true for Egg color. They will breed true for body type and muffs and beards. It is the color genes of the feathers that won't breed true. I believe in distinguishing the offspring of 2 purebred Ameraucanas of different colors as AM EE's, meaning that they are true to type and egg color with no brown or white egglayers in the mix.