What happened is this: My Sim was at a dance party with a friend. So she was in a group, though only with one other person. (I'm not sure if the grouped condition is significant, but mention it just in case.) She got into a conversation, which became a multi-person conversation. One of the NPCs in the conversation was an alien. This alien was not in my Sim's group, but was a part of the multi-Sim conversation. Said alien NPC used an alien power. Suddenly my Sim got a whole set of notifications that she'd discovered an alien in disguise -- one for each Sim in the conversation. Yes, every Sim in the conversation was tagged as a 'Known Alien' to my Sim. Now I have human Sims like Luna Villareal and Geoffry Landgraab marked as 'Known Aliens,' among others.
I don't know if there's anyway to 'undo' the tagging, but it would be nice. Hopefully this will be noticed and fixed -- that would be wonderful.
I've added this
I don't know of any way to remove the tag. There might be a cheat ...
Ummm . . . not really sure here. I am now using the MCCC mod and its option to disable autonomous alien abilities. So the situation no longer arises. Honestly, I've drifted away from TS4 quite a bit of late. Not playing very often. But I'll see if I can set up a situation without the mod and see if it still happens.
