what breed is this

[pinecone33]

does anyone know what breed is this, we have lots of chickens all different colors (black, white, light brown and white, grey) but this is the only one that’s dark brown and was brown at birth I don’t even know how this happened none of the other hens are that color.
the first two pictures are baby pictures but the last one is recent, around 10 weeks old.

 

[bigz1983]

I think it's a Black Sex Link.