No idea. Want a fellow researcher?Do you have any clue as to why pink would be the only color of an egg shell, visible on the inside of a shell, (from a normally blue egg layer line) or why if there are only supposed to be White or Blue shell color, with brown as a outer "paint", we could see in a bunch of medium brown eggs we cracked open today, the brown on the inside on the egg, where it should have been white?
I realize probably not. That's what I've been trying to figure out all day though. I'm thinking it might have to do with color suppressing genes(for the pink) but I have only come across one mention of that and aside from the abbreviation "pr" and that it affects this one affects the brown pigment I haven't seen anything else about it.
I think part of the problem is that few people have the same definition of a "pink" egg. Also, I'm thinking that if a hen can eat things and make her yolk yellower, the brown inside (palisade?) may be a similar thing with the shells—not genetics as much as the material the hen has to work with.
though it might not be fair to steal you for my own purposes lol.