This compilation of gardening guides from the Booth Museum library is dedicated to King Charles II, and advises your groundsman how to propagate trees, arrange your hedge mazes, and what flowers to plant when!
Someone mentioned this, and I never need very much provocation to talk about Charles II of Spain. And I’m going to connect it to OUAT.
This is by far the worst example of royal intermarriage in European history that I know of. The horror of it is described below the family tree. Over seven generations, Charles II had seven novel ancestors (meaning someone whose family is unrelated to the family they’re marrying into). SEVEN. There are three marriages between first cousins. That part I think we’re generally used to hearing about in history (and not really that long ago), but there are also three marriages between uncle and niece.
Two men in these uncle/niece marriages were widowers. One of the brides was only fifteen when she married her forty-four-year-old uncle. This sort of behavior may not have been common among the peons, but as noted by others, not uncommon among royals.
So in OUAT, Cora maneuvered her young daughter into a marriage to the man she herself was once engaged to. A modern audience recoils from it for a couple reasons, but would the people of Leopold’s kingdom have been repulsed because Regina was young? Probably not. Would they have been repulsed because of Cora’s prior relationship with Leopold? Maybe. Maybe not. I think historically you could argue that it would not be considered all that strange for royalty.