I had a stock pair locked up in there box until the hen laid. I do this with older cocks to guarantee fertilisation of eggs, any way, the cock is blue and the hen bch and to my amazement the 2 ybs are red ch. The hens dam is a red ch but I don't know about throw backs etc being true. If I was putting these ybs into an auction folk would question their parentage because of there colour.Im bamboozled as no other cock could tread the hen.ps. the other birds in the section are either ch or blues???? My conclusion is, throw backs do happen!!