It's profoundly strange to have any knowledge of the future; even this, as big and important as it is, is only a glimpse. There are a thousand questions she wants to ask, but doesn't know where to start; some of it, she thinks, she can probably guess. If Mulder didn't want to be on the birth certificate-- they wouldn't be able to work together, probably; it makes some sense, even if the idea makes her oddly uneasy.

"You don't really think we could've kept that a secret?"

From a child of theirs? His father's curiosity, his mother's hunger for proof? Surely he'd have figured it out.