Reply #1: All modern food crops are Genetically Modified in one way or another. [View All]

Thats what hybridization is; Genetic modification through the proxy of selection.

You simply find a mutant gene in an existing plant that does what you want, and through crossbreeding and selection move that gene into the strain of the plant that you are currently cultivating.

The modern genetic methods, however, allow this to be done much more quickly, and allows genes from plants that cannot interbreed with your food crop, or totally synthetic genes, to be inserted into the genome of your existing hybrid plant.

Prior to understanding genetic inheritance, you had to wait for a mutation to occur in your cultivated crop, and select those plants as the seed stock for the coming year. This is how the Native Americans hybridized corn from the teonactl grass.