head asplode
Ha, it’s the first thing I thought of too. And I own that movie on DVD.
Could the OP please come back and explain why they asked if it would be illegal? Oogy I can understand wondering about, but the question of legality has me baffled.
Siblings marrying other sets of siblings is common in towns/small cities with large families (such as Mexican communities, for example, with many families having lots of kids, and not that many families in town). I mentioned this to a Mexican-American friend once, and she said it happened quite often where she grew up. I had friends in this situation (which was why I brought it up to my other friend in the first place) who adopted a daughter of their siblings/in-laws, and you could hardly tell her apart from her new siblings, they all resembled each other so much. Genetically closer than cousins.