(written from a Production point of view)
David Moore is the son of Star Trek: Enterprise hair designer Michael Moore. He was cast as a Human school boy for the third season episode "North Star" and appeared later in this season as a half-Denobulan boy in the episode "E²".
According to his father, Moore was cast in "E²" because he had been "very easy to work with" on "North Star". (Star Trek: Communicator issue 152, p. 31)