I have 8 Faverolles chicks that I received from MPC. They are all supposed to be 2 weeks old today, but half of them have wing feathers & starting growth on their tail and body feathers...the other four still have their down, only partial wing feather growth, and no tail feathers. Is this normal to have this different growth rates among one batch of chicks? They all seem healthy & all are eating well...I am just puzzled by the difference.