I think we all knew a couple of things. Jon Snow is a Targaryen. He is the mixture of Fire and Ice. And that he and Daenarys were headed towards sexual relations. Another mixture of Fire and Ice. I've seen a lot of things written on the internet about last night's coupling. Unfortunately I didn't see too much putting things into historical context. The Westeros society of A Song of Ice and Fire is basically 15th century England/15th century Europe. And throughout history in the Christian and Jewish worlds, an aunt marrying a nephew/uncle marrying a niece was not necessarily frowned upon. Definitely not within the nobility whose marriage choices were limited and needed to focus on what was best for the state (Too bad Rob Stark was too stupid to understand this). The Habsburg Austrian and Spanish branches were particularly known for this before the Spanish branch died out.

From a genetic point of view, it would make sense to not have this kind of coupling as it could lead to problematic mutations (Looking at you Habsburg lips), but from a societal standpoint? What was true then about this kind of coupling/marriage is not necessarily true now. Times change. Mores change. How we view this has changed. But I leave you with this -