X2 what nicalandia said....
back stripes and dark black eye-liner = girl
big white head blotch = boy --
Sadly, I divested of those chicks in the photo above.
I think perhaps the dark-black girl grew up to look a LOT like her mother Robin. -- One may not be able to keep all one's hatchlings, especially when one is moving. sorry -- I will keep better track going forward.
ETA mother's hackles are in the photo with chicks.
Now--- I'm wondering about not the CREAM but the other part of the barring. Seems like UK birds have a light-gray color in the barring....but most USA birds have a darker - darker gray in the barring. Anyone else see it that way?
BTW also, I knew exactly which hen and rooster paired for all my chicks -- and had some of the medium light - the more silvery gray males and those 4 very dark downed chicks all from the same hen and rooster.
Here's the best of my projection -- the down color seemed to have little to no influence on the adult colors--- but I can't verify with 100% accuracy.
ETA, while i'm throwing things out there.... the color referred to as 'slate' is what pioneer kids took to school to write on -- it evolved into the "black board" -- really. So a medium gray may not be slate. JMO.