I have a blue marans and a black copper marans and my roos are very obvious looking, yours looking like pullets to me, but I am only going by the comb, Mine are only 4 weeks old also
Looks like they might be pullets to me too. I had my very first wheaten hatch this past weekend and I asked on the marans thread how to sex it. I was told that at about 5-7 days old, the feathers of a pullet will come out wheaten or brownish. The cockeral's will start coming out black because the wheaten roo tends to look a lot like the black copper marans aside from the color of a triangle of feathers.