Gattaca/WMG

On the trip to Titan something happens that puts the mission in jeopardy, and being the one who can "swim out not expecting to get back", Vincent saves the day...
Then either:
 * He dies saving the rest of the crew and is considered a hero. His body is checked when he gets back and when his true genetic code is revealed it sparks more relaxed gene laws.
 * He survives and upon return he either goes on about his life as Jerome or reveals himself and pushes for looser gene laws.

On the trip to Titan or back to Earth Vincent suffers a fatal heart attack.
Because the Straw Man Has a Point.

Director Josef kills the Mission Director BECAUSE one of them (or both!) had found out about Vincent.
Josef DID say he was willing to do anything to keep this mission on time... and re-screening to find a new candidate would've taken them just as off-schedule as anything.
 * Even if Josef didn't believe it himself, the thought MUST have crossed his mind if the Mission Director thought so, and gone "still worth it."
 * Mentioning that the Mission Director was suspicious about Vincent (and that despite not killing him, Vincent would certainly have reason to) is mentioned too often to be coincidental...