Genetic engineering refers to the ability to manipulate DNA, and ever since its invention in the 1970s it has been a source of controversy. Some argue that it allows scientists to "play God," which could have unintended negative consequences. However, genetic engineering also offers the potential to significantly advance the fields of medicine and agriculture. Through modifying genes, certain types of diseases and conditions could potentially be prevented or treated in a process known as gene therapy. In agriculture, genetic engineering has enabled the development of genetically modified (GM) crops, which can be more resistant to pests and extreme weather. This volume looks at the science and controversy surrounding this timely issue.