"For all his wrenching realism, Greengrass spares us something, says Amis: United 93 has no children in it. Yet when was the last time you boarded a plane that had no children?"

You might want to check into this one; it appears that Flight 93 did not actually have any children on board. (It was an early-morning flight intended for business travelers.)

Here is an internet source for the passenger manifest, with ages. The youngest passenger was 20 years old.