No worries! I totally understand where you're coming from because chick down seems to tie to different colors quite often.
In this case it's the genetics. Daddy is a Black Mottled English Orp (see my avatar) and this is what he looked like as a chick.
Mommas are Black pure Ameraucana. Their...
In the time it took me to take and offload these pics from the camera, a second baby hatched from one of Blackies eggs, and it's Mottled too! I can't believe it!
First baby: