Making Sense of GM

What is the genetic modification of plants and why are scientists doing it?
There are some big gaps between perception and reality about GM. This guide looks at what scientists are doing and why.

Published: 9 February 2009
All our guides are date stamped and reflect the scientific findings and knowledge available at the time of publication.

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Plant breeding has been very successful but it is an imprecise art. The new molecular technologies, involving both GM and marker assisted breeding (non GM) are changing this.

Prof Chris Leaver

Emeritus Professor of Plant Science, Oxford University

Did you Know?

The adoption of biological solutions such as insect-resistant crops, particularly GM cotton, is reducing the exposure of farm workers, most notably in India and China, to dangerous insecticides such as organo-phosphates.


We have found it difficult to point people towards anything that could give them a direct way into the debate without being overwhelmed by scientific detail on the one hand or polemic on the other. Faced with a likely resurgence of the GM issue, we went in search of straightforward answers. This guide is about what scientists are doing and why. We have asked a lot of people to help, from researchers at the main UK plant research institutes to farmers, toxicologists and people who could lay their hands on relevant material. Arriving at just 20 pages was tough, but here it is; we hope it helps you to cut through what you hear and to distinguish fact from misinformation.


This guide was produced in collaboration with BBSRC, the Genetics Society, the Institute of Biology, the Institute of Food Research, the John Innes Centre and the Lawes Agricultural Trust.

Reprinted in 2009 with support from the John Innes Centre, the National Farmers’ Union and the Royal Agricultural Society of England.

Reprinted in 2011 with support from the Biochemical Society, the Genetics Society, the James Hutton Institute, the John Innes Foundation, the National Farmers’ Union and the Sainsbury Laboratory.

What is the problem this guide is addressing?

Crop improvement, whether by GM or conventional breeding, is just one component of a wider social and economic debate about agriculture, food and the environment. But unless there is better understanding and well informed discussion about GM, it will be impossible for the public and policy makers to judge what crop technologies can contribute to food security and natural resource and climate change management; and it will be even harder for the research scientists in our institutes to increase our knowledge and deliver on the urgent demands of agriculture.

There are some big gaps between perception and reality. For example, conventional plant breeding already exploits crosses between plants that would not occur in nature or induces random mutations artificially with radiation or chemical agents, so it isn’t really more “natural” than GM. “Eating genes” is something that everyone does every day, whether they eat GM foods or not. GM crops are grown in 23 countries, so the world isn’t and can’t be “GM-free”. Discussion about GM also seems to have become a proxy for other much-needed discussions about food shortages, economic power of multinational corporations, food safety, farming systems and trade agreements, which go far beyond this technology and its applications


This guide continues to be really popular and was reprinted in 2009 and 2011. Following its launch, BBC Radio 4’s Today programme used the guide to start a conversation with contributor Prof Ian Crute and Peter Melchett from the Soil Association. Prof Chris Leaver was interviewed about the guide by BBC Radio Oxford. Farming groups in particular ask for Making Sense of GM and use it to help them explain GM at meetings and conferences.