CIA
not sure they'd trawl something like FB....
if the CIA or similar wanted info on you, i'm sure there'd be easier ways of getting it. we went to the US 2 yrs ago with our 11month dd. they insisted on taking a pic of her and her iris at passport control (i argued the ridiculousness of this which ended with being told that if i didn't co-operate, we couldn't go any further).
if they start that early, by the time you get on sites like FB, they'd already have a pretty complete profile.
Thankfully, probably after millions of complaints, the US customs only take your prints/photo etc if you're over 14.