Context: I posted this on Smashboards in a Smash shipping thread once the subject of Marth x Lucina was broached.
"Here's some Canon Law for everyone.
Can. 1091 §1. In the direct line of consanguinity marriage is invalid between all ancestors and descendants, both legitimate and natural.
§2. In the collateral line marriage is invalid up to and including the fourth degree.
§3. The impediment of consanguinity is not multiplied.
What this means is first cousins have not been permitted to marry in the Church for nearly a thousand years.
This also means that no direct descendants can ever be married. Great-great-great-great relationships included or whatever.
But here's the interesting part.
This Canon Law is based in the Natural Law. That is, it tries to reflect how nature deals with things. What happens with interbreeding is all sorts of strain on relationships and, more importantly, the real damage done to the products of their inbreeding by the process of nature.
Well, okay? So what?
The Church allows dispensations from (certain parts of) Canon Law.
It's obvious that Canon Law isn't built around time travel.
It's easy to see that someone might be so far down a generational line with no severe inbreeding as to incur no penalty from the natural law. Therefore, civil and ecclesiastical authority could shrug and be like "yeah that's cool".
Source: My cousin is adopted (in fact, all 9 of them on me mum's side are) and she's hot so I was wondering if I could marry her lel
Disclaimer: I do not support Marth x Lucina but here's for u guys ok your welcome
I found out some more neat stuff about the whole nobility marriage thing.
History buffs are undoubtedly well aware of countless examples of such dispensations granted to members of European royal families in centuries past. Often it was argued — convincingly — that it was politically expedient for the two cousins to marry, because their wedding would contribute to peaceful relations between their two countries. Sadly, the bloodlines of most royal houses became so intertwined that significant genetic problems eventually arose among some family members. The daughter of Spain’s Ferdinand and Isabella, for example, was apparently insane and became known as “Juana la Loca,” or “Joan the Mad.” And just a couple of generations later, Carlos, the eldest son of Spain’s King Phillip II, was born physically handicapped and mentally unstable. It is commonly understood that too much intermarriage between too many cousins wreaked genetic havoc within Europe’s royal families, leading to the various medical problems suffered by these and numerous other royals. source"