It just arranges natural mating of selected parents without any intrusion into genes. Not a big deal. Just a very small gene is added. Such attempts at calming worries about genetic engineering are very misleading. They give the impression that GE is a simple and safe way to change the genetic makeup.
Genes are very powerful.
To make the insertion succsessful, additional genetic material is included which makes a great difference to what occurs in breeding. It ensures that the inserted gene is active in the new surrounding. It counteracts the effective species protection mechanisms that prevent the uptake of foreign genes. Especially the promoter complex may cause unexpected effects and problems. The vector DNA is derived from bacteria and contains genetic code sequences that trigger inflammatory responses.