You remember who those two are, right? They were around for the first couple of episodes before unceremoniously dying by poison apples. Emily and Timothy were taken to Outpost Three because they apparently had the "perfect" genetics. We never get into what that means or why their perfection is needed before they die. But in the event that we get to see them again, this particular theory explains why their origins are so important. Reddit user AlfieBoheme theorizes that the two are actually the descendents of Kit Walker from Asylum.
Now bear with us here. Since there are obvious physical similarities between the babies and the two in the Outpost, this could be feasible. As redditor rwhyman1 clarifies, Emily and Timothy don't have to be the actual babies, but they could be clones of Kit's children that the aliens send down with each generation to learn more about the human race. The theory gets its legs from the fact that Asylum's aliens are shown to communicate through electronic interference with radio and TVs. AlfieBoheme presumes that the aliens have been watching over their experiments through time and the songs played on the radio in Outpost Three are actually them communicating with Emily and Timothy that they're going to be rescued soon. This actually checks out pretty well since the first song is about interplanetary messages and the other is literally about being rescued.
The only reason to side eye this theory (because as far out as it seems, it's not that far out for AHS) is the incest. That's a little too Game of Thrones for our liking!