There are three distinct races of ponies in Equestria, as opposed to a common misconception that pegasus and unicorns are special variants from the basic pony. The episode "Hearth's Warming Eve" as well as the iOS app Twilight Sparkle: Teacher for a Day and its Ruckus Reader version Twilight Sparkle's Special Lesson explain how the three races came together to form the land (the episode tells less of the story but in more detail, while the app tells more of the story but in less detail). The exceptions to this are the rare Pegasus unicorns, who possess traits of all three races. Genetics do appear to play a role in determining species: in "Baby Cakes", Mr. and Mrs. Cake (earth ponies) have a set of pegasus and unicorn twins, which Mr. Cake ascribes to these being from their long-distance r