Thank you for your important question. The definition of a “GMO” or a transgenic organism refers to an organism containing a gene inserted by man. This is quite evident when one reviews the criteria for release of these organisms as defined by the Joint Food Standards Program of the Food and Agriculture Organization of the United Nations and the World Health Organization, as well as Codex Alimentarius Commission (reviewed in Steiner, H-Y, Halpin C., Jez J., Kough J., Parrott W and , Hannah, LC. 2013 Evaluating the Potential for Adverse Interactions within Genetically Engineered Breeding Stacks. Plant Physiol, 161: 1587-1594.)
The gene need not be from another organism or from a bacterium. For example, our lab modifies corn genes and puts them back into corn and this is still considered genetically modified. Part of the “approval” process involves a determination of the position of the new insertion and some assurance that this new insertion site is not in a gene important for the plant or for food safety. Also, we use sequences from a bacterium for the insertion process that do not normally occur in maize (although they are now found in other approved maize transgenic events).
The point that the distinction between transgenic and non-transgenic is murky (and in some cases nonsensical) is quite valid. For example, the bacterial sequences that insert the genes into plants to make transgenics mentioned above do this naturally in nature and yet this is not regulated when it occurs in nature. Also, there exists much genetic variation in nature. Two corn inbred chosen at random are more distantly related than man is to the chimpanzee, yet we are not really concerned about how this “natural” variation affects food safety.
I look forward to the day when this issue of classification and approval is based more on science than it is on politics and fear mongering.