I've got 2 batches of chick's one is 4 weeks old and one is 3 weeks old. They are all a straight run mix of white leghorns and cornish rocks. There is one chick that has a huge comb and wattles. Seems excessively big for a chick it's age. I'm guessing this means he's a rooster. As of now they all look pretty close to the same size. How old will they need to be before there is a big size difference where I can tell which is which? I'm guessing size is the main thing to tell which is which? Thanks.