That's what all females say Just kidding, I can't give any other educated answer. That color just may be in their genes from earlier generations, like kids having different shades of hair color than their parents. Post some pictures, I'm sure they're a beautiful color.
Chicken genetics can be a very weird thing, and complicated.
I had a hen who was a barred rock and a rooster that was Delaware. She would lay her eggs in my garden and hatched out 5 peeps from 9 eggs. I inspected the eggs and all of them were her eggs, they were all the same coloring/shape etc. Of the 5 peeps, three looked like little barred rocks and two looked like little Delawares. The one barred peep was taken early on by a hawk, but I still have the four peeps---all boys. Two are a slightly lighter color barred rock and two a full on Delaware and look EXACTLY like their Daddy. At the time I was positive because of the young age of my other hens that there was one father and one mother of all 5 peeps.Two of the four crow EXACTLY like daddy, however one is a barred and the other is the delaware the other two (again one of each) crow with a different beat and sound different.
Unless you know the grandparents and great-grandparents and their breeding it can be tough to pick color.