Board Thread:Questions and Answers/@comment-27810039-20160217103443/@comment-24152851-20160221113718

It's not a retcon, it's an alternate explanation for something already there. Basically a clarification of something not clearly explained before. They never said Gwen was not alien before, and they never fully established what magic was. In AF, they basically explained that magic in Ben 10 is defined as the ability to manipulate mana. Before it was just read some spells, weird stuff happens, no one knows how or why.