I have a pretty weird story that happened to me a few years back. When TS3 first officially ended, I decided to finally add in the nrass story progression and master controller mods. I was playing a legacy challenge in Sunset Valley and would periodically check in to see how the other sims in town where doing. One day I sent my sims teens to school as usual and it said they had met two new teens I hadn't heard of before. I checked their relationship panel and it claimed they were the children of Gobias Koffi. It started to get weird when I realized both of these teens pictures were just silhouettes so I couldn't see what they looked like in the relationship panel or the lot photo when you go in to edit town. What was even weirder was the fact that, as far as I knew, Gobias hadn't previously had a wife or children before. It fact, the last I had heard from him was that his dog had just given birth to puppies...
I got curious and switched over to his house to see what was going on. The two glitched teens, Gobias, and the dog were there but no sign of the puppies or a mom so I checked the family tree. Turns out they had Gobias listed as the father and the dog as the mother! The game had somehow turned the puppies in to Gobias' kids. I was able to fix the teens so they weren't glitched anymore and, with the help of the mods, fixed the family tree so the dog was no longer their mother. I uninstalled both mods not to long after and haven't used mods since.