What is happening here?

[ChickInnHouse]

To start with the parent flock; I have a large number of RIR( gotten from tractor supply over the years, so this is potentially the problem of the hens not being genetically good for this). Also in the flock, are a handful of crested cream legbars. The rooster is a RIR(again supposedly, with the way TS goes).
The babies in question:
The RIR babies

I'm pretty sure are the rather buffish looking ones, and the CCL are the chipmunk. My problem is, why is there so much variation in the pattern? None of them have the white barring mark on the back of the head that I was expecting on the boys. Am I supposed to be looking at the amount of head spotting, or the actual base color?

Thanks in advance!

 

[JedJackson]

The head spots often don't show in red or striped chicks, and these are mixes as well. I think you'll have to wait until they're around 6 weeks to start determining gender.