How do you tell the difference between Polish, Sebrights, and Buff Orpington chicks? My Polish are about 7 weeks old, the Sebrights 8 weeks, and the Orps are about a month. Any tips on telling the gender? One of my Orps has a bigger comb than the other, so I think it might be a roo but the others look the same so I'm not sure what to look for!