Okay, so this is my opinion on the matter! I'm getting fed up about the whole topic so I'm just going to lay out some facts, either you agree or disagree is up to you! So hear me out before you go all crazy fangirl on me,
Technically it is incest because England raised America (which if you look up the word incest, it counts) so thus they are family, but when the two had the revolutionary war which in affect had America become independent. Therefore it was incest but now isn't, all in all, they were 'brothers' but not blood related and the two cut the ties.
Please do not hate or anything because I am on both sides because, yes I do ship UsU