With the rooster, it's white that just didn't molt out. Not caused by a specific color gene, might be nutritional or some sort of random mutation. The hen is mottled.
Also mottling except for the last one. That looks like birchen with dark brown removing the black from the chest and allow the silver ground color show.
There are only 4 genes that will strip pigment producing white. They are dominant white, recessive white, mottling, and barring/cuckoo. Barring is dominant, mottling is recessive.
These 2 are young, what do you expect will happen with them? They are showing the brown around the hackles already.