We are new to chicks/chickens. We have 3 1/2 week old chicks. Two are supposed to be RIR and two are supposed to be Red stars (Red sex link). When we got them at the feed store, they were in separate bins, but the guy at the store was a little confused about which were which. They are very similar in feather color so I can't tell. 2 of them had black lines on their heads and he told us that they were the stars, but I read in BYC that that's a trait of the RIR. Also the ones with the black stripe had just a black spot on their beaks, the others had much more red on their beak. Now that they are feathering on the head, I can't see the black stripe and can only tell the pairs apart by their beaks. Can anyone help me determine which are which? Here are 3 of them at almost 2 weeks. You can see the line on the two in the back. Here are two of them at about 3 weeks. Thanks for your help!