Today there are 6.4 billion people on the earth. By the year 2050 there may be 12.5 billion . There are a lot of people to feed. We need more  and more food.
One way to produce more food is growing stronger plants. For thousands of years, farmers have made plants better. Every season, they pick the best plants for the next season. It works very slowly. Since 1983, scientists have been able to change plants more quickly by changing their genetic（遗传的） material. Foods from plants grown in this way are called genetically modified(改变的) foods, or GM foods.
By changing the genetic material of a plant, it is possible to make new plants. They make plants which are strong against plant diseases. They can also help in our diseases; a kind of rice is being prepared , for example , which stops people becoming blind.
Rich countries produce GM foods because they are easy to grow and bring in more money. Poor countries are interested in them because they help produce more food.
GM plants are not natural. No one knows how good or bad they are,. Making GM foods is only one way of feeding people in 2050. There are strong feelings against them, because they are unnatural. They may feed people , then hurt them or their children later. But both rich and poor countries are interested in their use, and they are not going to go away. In 2050, we may think differently about them.