Hi we have 2 pure white very large swans with bright orange beaks. This spring the had 3 babies. They now are full grown and as large as the parents. How can they have one pure white with orange beak, just like parents, and 2 Brown with black beaks??? The 2 brown swans are slightly larger than the white baby. We are on Barnegat Bay at the Jersey shore, can the salt change the color? Thanks