Ideas
I also noticed this. I had just created and moved in 2 unplayed households, both of them single young adults, and within like...3-5 in-game days they both had adopted 2 children each. I think one had also adopted a dog. Um, what? Seems like the chance of these adoptions should be lower, especially on a long lifespan... At the current rate, every household is going to be full with children and pets. Needless to say, I turned off the adoptions in neighborhood stories, until it's tuned down a bit. (Well, except for the households where it makes sense they'd be cat ladies or something like that.)
Agree, they need to lower the chance of adoption or limit it by specific traits: Cat, Dog & Horse Lover, and Family Oriented. So the unplayed households not filled by this mess.