I am hoping for a girl, but would like other opinions. No red to the comb (it is just now getting bigger), hackle feathers seem rounded, but I only have the 1 d'Uccle and have nothing to compare it to.
I am going to hazard a guess and be a bit out of character regarding sex prediction (by being optimistic) and say female. But I can not see if there is a bit of red starting at the base of the comb or not, and four weeks old is too young for male sex feathers. You should be able to tell more definitively in about two weeks.
i am hesitant on this one i see coloring that would indicate a cockerel, the darker buff feathers (the same coloring my cockerel had that i noticed only after going back through pics)