To prevent serious imbreeding most can travel as frozen eggs and sperm.
There is this, but also having a functioning crew on arrival is important, since the trip will span several lifetimes (or generations... "generation ship").
Hypersleep is out, since that would null the entire premise of the story, and androids seem to be unavailable with the given tech.
A genetic databank (frozen eggs and sperm) seems like something that wouldn't really be relevant during interim space, and possibly a point of destruction during the major mutiny that was outlined as a major plot point. Also-- it could be that a genetic databank was considered by mission planners, and dismissed for reasons of human psychology.