Many duck enthusiasts don't believe that Pintails contributed to the acculturation, because a Mallard dirivative X Pintail renders a sterile duck due to chromosomal differences. However, it is possible for a rare mutant Mallard-Pintail cross to pass on its genes to generations to come, leaving it possible that the Pintail did indeed contribute to the specimens. David Holderread, one of the top waterfowl breeders in the United States, has said that he has observed various traits in the Australian Spotted that are distinct to Pintails.