I did NOT know that old dude was my son. I got to the Institute, after ages of side quests, and I am gearing up to kill everyone in the place for the Brotherhood. I find this little kid, who I THOUGHT was Shaun. The one that was stolen from me. Coincidentally I was using Kellogg's pistol, cause I like V.A.T.S. Then an old, vaguely brownish guy, who looked kinda like my (now dead, thanks to Kellogg) wife. He did a thing, and my child got all slumpy. For a moment I was shocked that Bethesda would kill a child on screen. Then I queued up every V.A.T.S. shot I could on the man's face, even before he could speak. Then I made it look like he had a heart attack that violently removed his extremities, leaving him on the sofa. Fought my way out, did some more Brotherhood stuff, and then. I do a little preemptive Googling for my options from here, and I found out the child was a robot, and the old man I ruthlessly, systematically dismembered for "murdering" a child was my son!