After leaving Benjamin's mansion, Jack went ahead said goodbye to Anita. Wendy and Jonathan had already left, going somewhere on a date.
And after leaving the residence, Jack began thinking once again. Everything was pointing towards the strongholds. That implied that, the strongholds were involved.
The first time that he felt that there was something wrong was when Erick said that, he looked like someone. And, no matter how much he tried asking him, it was as if Erick was prevented by something from ever talking about the matter.
The second time was when he met with Maxwell. During that time, it was claimed that he looked like someone once again. And, Maxwell went ahead and told him that, it was true that Jack looked like his mother.