I have ~50 chicks with an assortment of breeds. Most are supposed to be sexed pullets but 20 were straight run and there may be sexing errors with the others. The question I have is at what age (weeks/months) can you be pretty certain about the sex of chicks? The breeds we have are BR's, BO's, RIR's, NHR's, EE's, and light brahmas--these are supposed to all be pullets, and dark cornish and cuckoo marans--straight run. They are almost 3 weeks old now.