When genes from other species have been transferred to an organism, we are talking about a genetically modified organism, or GMO. Such inter-species gene transfer is described by a tomato to which a cold-tolerant gene has been transferred from flounder. Gene transfers can improve the resistance of crops to plant diseases, pests, unfavorable growing conditions and herbicides. No gene transfers have been performed in animal breeding, although gene transfer between animal species is possible. Animal cloning is possible, and several dozen animal species have been cloned around the world.

Dozens of genetically modified or GM plant varieties have been developed. The most important GM crops are corn, soybeans and rapeseed. These are already used quite extensively for both food and animal feed. The majority of soybeans grown in the world are already so-called GM soybean. However, animals raised with GM feed are not genetically modified, as the feed is broken down in the digestion of the animals. Genetically modified plant varieties have been called upon to help with world food shortages and the problem of hunger in people in developing countries. Developed in the 1990s, the so-called golden rice has a gene that produces a vitamin A precursor. Vitamin A deficiency causes blindness and underdevelopment.

On the other hand, GM seeds, as well as the fertilizers and pesticides needed to grow them, are protected by patents from multinational companies. The farmers who use them are completely dependent on the pricing and regulations of these companies.

There are strong opinions about the use of genetic engineering in food production. In order to be able to take a valid position, it is necessary to understand the principles of the function of genes and to know exactly the ecosystems in which genetically modified species are part of food chains.