One can argue that any exploration brings risk, and taking one's family drags them along into that risk. The United States was a risk for enormous numbers of families, and children had little say in the voyage nor their role in the new world. In fact, most the world's children are still locked into their parents circumstances. Only in recent years has the choice for young adults been much wider, but we may need to narrow options in the future if we want to leave this third rock from the Sun.Those of us who worry that their doing so limits the children’s right to an open future should be even more worried by locking children in to a much greater extent than dreamt of by the Amish. After all, adults can, and do, leave Amish communities. But no one gets to leave the generation ship, and few or none will get to choose what role they play aboard.
This may be the twisted morality of species expansion and protection. For instance, we need the non-democratic military to ensure a democratic society. Does that make sense? Such inconsistencies will be with us for some time. That does not mean we do not try to find new ways to expand options, but of we may have to settle for a less perfect "world" if we want to settle another world.