Most times it's a genetic issue, once in a while its an incubation issue
I couldn't read ALL the pages here. Is cross beak + one small eye a problem with how they were in the shell or a genetic issue? We have a cream legbar rooster chick who has a mild crossbeak and one small eye. I really wanted a blue egg layer! I am thinking of breeding him with one of my white egg layers but if it's a genetic issue, I don't want to breed him. If he just grew that way, then it should be fine. We can't have roosters so we will eat him once he starts crowing, but we should have a couple of weeks when he is fertile and mating before we have to cull him. Just trying to decide whether he is breedable or not (and I don't care that the chicks would be mutts; they are just for our own fun, eggs, and meat).