Out of my three 6 week old Birchen Marans, one is a gender mystery. Picture of her/him is below. He/she is a shrimp, 1/2 the size of both the cockerel and pullet hatchmates. He/she feathered the slowest (including tail and back feathers), and has a comb much smaller than the cockerel, but slightly bigger than the pullet. Comb and wattles are still very pale, like the pullet.
This is the known cockerel

another picture of the known cockerel

this is the one I can't tell -comb looks bigger here

the unknown gender in the front, pullet in the back

unknown gender in the front, pullet in the back, Combs look similar in size and color here.

This is the known cockerel
another picture of the known cockerel
this is the one I can't tell -comb looks bigger here
the unknown gender in the front, pullet in the back
unknown gender in the front, pullet in the back, Combs look similar in size and color here.