When you hand selected them did your kids pick out the ones that had yellow on their wings and belly? Although this isn't always true, Rhode Island Reds in their chick down can kind of give you an idea of what gender they will be. The females will have a darker red down color and the males will have lighter down with yellow patches. This happened to one of my friends who picked out the yellow colored chicks in a straight run bin of Rhode Island Reds and received all cockerels.