So i have been to the institute and i accessed the terminal. I found a list of names and professions. Among them was Lucas Sims (who i thought was the mayor of megaton in fallout 3), the merchant who goes around selling armor ( i forgot his name but i thought he worked for Stockton), and trashcan Carla. What does this list mean? Are those people working for the institute? I tried killing Carla but she isn't a synth.
I know this answer is super late but I was busy looking up who the informants were as I forgot, I intend to go on a rampage :-)
BUT I noticed something rather interesting with regards to this. At my Sanctuary there was a spat between two settlers where one was going mental accusing the other of being a synth, I settled the spat with both characters going back to their daily duties (Used some chems to boost my charisma) and I left to go do my routine junk scrap and trade to Trashcan Carla who just so happend to be there as it was all going down. Well this was before I got to the institute so I was none the wiser but the settler they accused of being a synth just disappeared, at first I thought it was completely random and some sort of bug or glitch but then when I found out about Carla it made logical sense as to what happend to my settler.