Board Thread:Character Discussion/@comment-5118208-20141108143108/@comment-5106672-20141117063128

Well, so far the only humans with confirmed innate magic are: Emma, as a product of True Love. Zelena, who was wielding magic as a days-old-at-best baby. Elsa and Ingrid, who have their own special brand of elemental magic.

All the others, either the thing was not addressed, or they had to be trained. We never saw Cora or Regina accidentally unleashing magic before they met Rumple, even though we saw both in situations that could have triggered it, if they had had it in them. Wath with Eva exposing Cora's pregnancy to Leopold? Or tipping her when they next met – the latter would have especially been enough for her anger to burst into magic. Similarly, Regina's distress at Daniel's death could have triggered her magic, had it been innate; instead, she later had a great deal of problems with it when, for instance when it was first brought to Storybrooke. Also, Anastasia seemed completely non-magical in the Enchanted Forest, and we've seen non-magical people, such as Belle and Neal, casting spells, although with all the ingredients prepared by magical people. Thus, I think we can be quite sure magic is an acquired skill, with very few people being born with it.