Who is the Father ?

My dog finally gave birth to 5 puppies after so much of waiting. haha. The vet had given the date a week back and we were desperately waiting for the puppies to pop out :D . Finally it did.But after the puppies are born we are very eagerly waiting for the doc again. Why ? Coz to know who the father is. Since my dog , Sofi , is a german shepard and is brownish n blackish.It has given birth to all black puppies and they are purely black.So who is the father ? But m glad she made it . :)