The use of gene scissors is not as uncomplicated as often suggested. A part of the problem: the gene scissors have to be inserted into the cell before they can be activated. In a first step, the DNA for the gene scissors is usually introduced into the cells of plants and animals, often by using additional aids such as genes from bacteria. This process frequently results in additional genes being unintentionally inserted into the genomes of these plants and animals. There are many possible consequences, e.g. unsafe and problematic substances can be formed in the organisms. Plants and animals can also become more susceptible to diseases if genetic defects are caused.
Errors made when using gene scissors can be easily overlooked if the actual complexity of the procedures is disregarded. This is the case with cattle that were genetically modified in 2015/2016 to make them hornless. It was only in 2019 that scientists found genetic material of the bacteria used in the process had also been introduced into the genetic material of the cattle. Amongst other things, they found complete DNA-fragments able to confer resistance to antibiotics in the genomes. If the genetically engineered cattle are used for breeding as planned, the unwanted genes can spread rapidly through dairy herds.
This example shows: if genetic engineering methods are used in agricultural plants or animals, all resulting organisms must be examined in detail. Otherwise, unintended changes in the genome can easily be overlooked. The use of genetic engineering must not lead to the spread of animal diseases or endanger our sources of food.