White is a partial dominant gene, so bred to any other color makes pied birds.It’s interesting and exciting what comes out of hatching I had 3 solid white Muscovy females and never got a white duckling now I know why is it only white to white produce them?
So I shouldn't get into how homozygous white and heterozygous white are both white... but heterozygous have a black cap while homozygous have no cap. But, if you breed a pied heterozygous white duck to another pied heterozygous white duck some of the babies can come out pure white with a colored cap which matches the parents color rather than having the black cap.... But, if it's heterozygous white with pied parents, shouldn't the danged thing just be pied? 

