I ordered day old chicks from one of the most popular hatcheries and paid for sexed pullets. I know vent sexing isn't 100% accurate, but up until now my pullets were always pullets. They are about 2 months old now, and one is growing a full comb and her wattles much faster than the other. They probably had different parents, but they definitely hatched on the same day. These are production reds. You can see how the one still has a small flesh colored comb and the others is growing and red.