Double Purity tells the moving story of the reunification of two identical twins, the cultural divide between them as a result of the forced adoption of one twin by Chinese authorities, and the effects of the separation on both girls and on their families. Along the way, Barbara delves into China's recent historical and political situation, telling the story of its brutal one-child policy, which came into effect in 1979, and the corruption and trafficking of children that emerged as a result. Many families aborted or abandoned children to comply with the law, and in 1992, when China opened its doors to overseas adoption, many were given up to orphanages. Babies were a valuable commodity, with orphanages receiving a 'donation' of $3,000 for each adoption. Over time a corrupt system grew up to increase the supply of babies, including many forced seizures of children.