@Cynic
name checks out...
that said, it was not that uncommon with royalty back In the day so its at least thematic.
Royalty had some really funky defects thanks to inbreeding that people forget was a thing thanks to the paintings.
Also, just to play devil's advocate here. ( not that I advocate incest, but just to dismiss some of the overexaggerated view on it...
and because I like discussion unusual topics with people. )
The problem with incest is fairly minor as long as its a one-time thing and the people are healthy to begin with.
With modern technology, it's not really a huge problem as the risk for defects is pretty minimal the first generations if something does happen as well.
Once it starts being a regular thing, that's when you get a problem tho as if you do it too much it can really fuck up the future generations...
That is ofc assuming you are going to have kids, you could always adopt a kid and avoid the whole thing altogether. ( not that its a likely event in this setting, but still )