Zak was a quiet child. He didn't speak until he was five years old, after which he spoke in complete sentences and remained, largely, quiet. Compared to many of the other members of the Atlantis Expeditions, he was intellectually unremarkable, graduating at 21 with a bachelor's in Earth Sciences from the University of Ohio. Even so, he had a way with plants and was hired at the start of the Stargate Program to study plant samples brought back from off-world. He was chosen to join the First Atlantis Expedition as one of the American representives. Following the recovery of the Tria crew, he was almong those who requested to remain on Atlantis.
During the Second Exodus, he took up a teaching position at Duke University alongside fellow former First Expedition member, Brandon Nelson. Significantly, although they took several thousand dollars worth of crop seeds, the university chose not to press charges against them, leaving him one of three Émigrés not wanted for anything more than treason by his goverment.
Additionally, he has been in a relationship with fellow Émigré Brandon Nelson since July 2007.