Chosen by whom implies that Q is a larger organization than I previously thought...perhaps Q is part of the NSA but still closely positioned near the POTUS (BTW the entire use of someone like Q fits completely with Trump's trickster side...that's why he was sent to NYMA as a teen).
And how were they chosen...and did they know they were chosen?
Are some autists chosen and others not?
being in existence and having demonstrated their effectiveness they were chosen as fertile ground for planting the Q seed.