The world is growing more and more genetically modified (or engineered) crops (GM crops). In Argentina farmers grow almost only GM soy, and no conventional soy. It is a controversial subject, since genetic engineering has many advocates and critics. The positive sides of GM crops are that it can create higher yields and incomes for the farmers. Those are the main objects of growing GM crops. Critics, on the other hand, say that GM crops have bad effects on the environment, and the risks could be too high. For example GM crops can spread to neighboring farms, where organic crops are growing. Many scientists claim that nobody really have enough knowledge of the effects of growing GM crops, and therefore thorough risk assessments are needed to examine the effects and possible risks of growing GM crops before starting to grow them. Politicians, too often, make decisions on false scientific grounds, when they claim that genetic engineering is a safe and precise method. The large corporations developing GMOs are heavily influencing political decision making. Scientists have studied the genetic engineering process and the results show that the method is not precise. It is difficult to know exactly what gene is transferred, and where it ends up. It is also important to discuss the precautionary principle in the decision making process.