ndjvjjdjf idk how my eyes completely skipped that "married within the family" part, for now i shall ignore it and assume her parents are distant relatives .. mmhm
That usually means they are cousins. It could be direct cousins or in 2nd or 3rd degree. If i'm not mistaken, at that time period they would call the cousin of their cousin their own cousin like there was no distinction. So it's not too long of a stretch to assume they are somewhat distant related by blood.
But just a piece of random info: Darwin married his direct cousin and blamed himself his sickly children
"Having inherited the vivid red many in the Ludran family are born with red features. Genes of my beloved parents, who married within the family" Wtffff eww not the FL being a product of incest I know it was a thing back then to preserve lineage but I don't need that bit of realism in my fantasy historical genre! And I was just thinking the parents were a gorgeous couple but no the fl is giving Charles the 2nd.