Chicken birthmarks?

[BaileyBirds]

Do chickens get birthmarks, or pass them down?

The internet hasn’t told me anything but I’ve been curious for a while because a lot of our bigger chicks over the years have had this exact same black spot on their backs!
They’re all mixed breeds from our flock so no there’s telling what it is.

 

[Amer]

It looks paint (caused by one copy of the dominant white gene on black.) It's typical to have that sort of pattern with paint.