Actually what I really think mine are is second generation sex links. I don't know where the OP got theirs but mine may very well have a sex link mom and dad which would mean they would have that coloration. Breeding a sex link to a sex link will have that effect, although the offspring will...
I suspect mine are a cross of some sort, I don't really know. I only posted it because they are very similar in appearance to the OP's chicks. None of mine hatched white and a couple of them are showing some pretty obvious signs of being roosters without being white which is why I assume they...