fallout theory: YOU were the son
In a universe where memories are very easily fabricated and replaceable I would not put this out of the question???? It would explain why the Sole Survivor is such a fucking generic milquetoast white picket fence boring person. Their memories are fabricated from pre-war media and written accounts.
They’re a synth planted in Vault 111 by Shaun. Shaun’s actual parents died in that Vault after he was taken like literally everyone else and as Shaun aged and discovered his illness, he knew he needed a perfect replacement. He fabricates the Sole Survivor’s past life and tries to make it as idyllic as possible within the confines of the Hell that pre-war America was in order to ensure the Sole Survivor’s loyalty to him as their supposed son, and to make sure their morality hasn’t been poisoned by The Commonwealth. He gives them a vendetta against Kellogg to A) clean up the last of their rogue agents, since he’s been made obsolete by gen 3 Coursers and B) to test the Sole Survivor’s ability and loyalty to their son.
He needed to create someone utterly loyal, the most perfect synth, one that has no doubt in its mind that it’s human. All his research with the child synth was a cover to develop the necessary technology to make the Sole Survivor, which he himself did craft with his own DNA, which does make the SoSu his child all along. He crafted his perfect successor.