Interesting.Yeah, it's a gene # deal like the muscovy/mallard cross that results in mules. One of our local parks (10 years ago at least) had an African type goose that paired with a Canada gander. They raised 3 goslings - sort of a dilute Canada coloring with orange feet. Mother died that winter but the young birds are still alive and fly with the resident Canada flock. They stand out when they are foraging as they are somewhat larger and more blocky. Whenever you see one the other two are close at hand. Makes me wonder if Canada 'families' hang together when they mature.