I can only imagine the look Monroe and Rosalee would give anyone who called their children a “litter.” I would just back away slowly and let the combined wrath of the sweater-clad nerds-in-love of Team Grimm descend upon that unfortunate soul. xD

I think it probably doesn’t work the same way for Wesen as it does for animals. Rosalee had two siblings but they were different ages. Monroe, as far as we know, has no siblings at all. Lt. Orson had two brothers and Angelina had two brothers, but there was no suggestion of twins or triplets anywhere there, either.

The way Bud talks about his family implies he has several kids, and somehow I always headcanoned that he had between 5 and 7 kids all together, but I don’t know that we’ve ever gotten a concrete number so it could be as few as two. And we saw a rabbit-Wesen not too long ago who had only two children, and rabbits are known for multiplying like…well, rabbits.

So I don’t know if it’s something that makes sense because they’re Wesen necessarily. It could just be luck of the draw.