But maybe the others were the original partners in the experiment...and something happend (the button wasn't pushed or they used to computer for something they weren't supposed to.) They fled the hatch and now wander around radiating nuclear waves or something. It's quite possible they would be interested in children.
What difference would it make about the gender of the children? Alex was a girl, right? And Walt and Aaronare boys...I don't understand that part.

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