Why are siblings often so different? Are “only” children lucky or disadvantaged? What are the long-term effects of birth order and sibling relationships? This program underscores recent theories that suggest relationships among a nuclear family’s children—rather than those between parent and offspring—are the most meaningful to an individual’s growth. Monitoring a group of 25 six-year-olds, the program follows experiments that highlight the significance of sibling rivalry and bonding. Among the lively subjects are James and his older sister Bernie, whose relationship is tested by their unstable living situation; twins Alice and Charles and their intrusive younger brother William; and Het Shah, an only child whose parents fear they have spoiled her. A BBC/Open University Co-production. Original broadcast title: Flesh and Blood. Part of the series Child of Our Time 2006. (60 minutes)