Of course but it doesn't have to be. There are tons of fruits that make great tasting marmalades. After watching the Mexican episode of British Bake Off I don't care about their opinions on food authenticity.
The amount of fruit and consistency is more important to the outcome of a marmalade or jam then the use of citrus fruits. A lot of recipe sites are flat out wrong about this and state a marmalade has to contain citrus, or worse, Spanish Citrus. If I make orange Jam is it automatically Marmalade? If Korea puts corn on Pizza, is it not Pizza anymore? So as I stated, yes it is about how countries and people deem food authentic.
People who think any food has to be made one way because that's the way it was made "originally" are missing out on potential. Most food origin stories are also stretched truths, lies, or even historically selective for political reasons.
