All hens start with laying smaller eggs and they slowly increase in size. Egg producers weed out any eggs that are perfect and they use them in other packaged good. Eggs are sorted into sizes so every egg looks identical. My egg take for a day is all over the place as far as shape size and whether there's gunk inside some eggs.
Producers use mostly leghorns and various sex link breeds in their operations, so yes you have some breeds used.
Producers use mostly leghorns and various sex link breeds in their operations, so yes you have some breeds used.