Science fiction by definition requires a lot of suspension of disbelief. But predicating a book's premise upon a civilization's most important custom being endangering and winnowing out their greatest resource, their children, is just absurd. The entire civilization exists in a tin can so it doesn't have young ones to spare. A fist size meteor at any time makes them all go poof. It's a ship. One ship. The loss of even one youngster could be the fatal blow that leads to extinction. Capiche?