At 4 months old none look like roosters, but beards and top knots can mean it takes longer to see any facial indicators. I took a second look at the brown one in the third photo as it has a bigger comb, but with a single comb I'd expect it to be bigger on a cockerel at 4 months old than it is with bigger wattles to match. They are all beautiful chicks - I love that black and white one!