So everything I understand (limited) about the barring genes said that when the roo is Barred Rock and the hens another breed, the offspring (if they turn out barred) will have the barring coloring of the female Barred Rocks. That it takes 2 barred rock genes to make the male barring coloring.
HOWEVER, I have 2 mixes that have taken on the male barring coloring. Both from the same hen (Rhode Island Red) and roo (Barred Rock) so maybe her genes have something to do with it...the 3rd chick from this pair came out with the female BR coloring. I just find it curious. I 100% can't tell sex by the coloring, right? Just because they LOOK like a boy, doesn't mean they are?