Hello! I have two barred plymouth rocks and two rhode island red chicks all about 2 1/2 weeks old (or so I'm told). We got them on March 17th supposedly about a week old. The two rocks seems to be developing at different rates, one of them doesn't have nearly as many tail feathers as the other three. Is she just developing more slowly, or could she just possible be a few days younger? Sign of anything else? In the picture, the one on the right is standing a little taller but you can tell the tails are different. We were told that they were all female, is it possible that its a male? Any thoughts?