My father in law decided to downgrade the size of his flock and gave my family most of them. They're a mix of barred rocks and what I was told were black rock hens. The roo is also the black rock. Are the black rocks the same as black sex links? What is the tell-tale sign to sex them at birth? Does the lineage/sex linking continue when a black sex link roo mates with a a black sex link hen? What do you get when a barred rock mates with the roo? Thanks for any help.