Genetic engineering is the direct manipulation of an organism’s DNA. This process can involve deleting genes, cloning existing genes, or inserting genes from other living creatures. Genetic engineering has already been applied across many fields, most significantly in medicine, research and agriculture. It has been used to create crops that produce their own pesticides, rabbits that glow green under black light, and microbes that excrete vaccines and hormones. Due to concerns about their health effects and unpredictable interaction with natural organisms, genetically modified foods and pets remain controversial in many countries.