Board Thread:Wiki-Related Discussion/@comment-25315804-20161129043202/@comment-26041252-20161129052857

I think fairies are a different species; apart from the distinct culture and wings, they're also a different size. Blue has made it clear that fairies are "naturally" small, and only become big when they choose to, which would be unlikely if they were originally human. Fairies can become "human", but they're not regular humans. In 3x11 Hook was able to identify Tinkerbell as a fairy even though she'd lost her wings, which points to some physical difference. The nuns of Storybrooke, even though the curse made everyone "human", are still immortal and apparently can transform back into fairy form. They're also immortal and (at least the powerful ones) are linked to a star, which suggests they were made that way.