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How can a transgene be passed from a genetically modified organism to its offspring?

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Rows of genetically modified barley plants grow in an outdoor test plot in Germany, with a yellow marker labeled 3 and protective netting overhead. — genetically modified organism Genetically modified crops are assessed for their impact on environmental factors such as soil quality.

A transgene is passed from a genetically modified organism to its offspring because it integrates directly into the organism's chromosome, becoming a stable, heritable component of its genome.1

Once the transgene is incorporated into the genome, it is transmitted to subsequent generations through the standard mechanisms of heredity. During the formation of sex cells (gametes), the genes located on chromosomes—including the transgene—are segregated and passed on according to the principles of Mendelian inheritance.12

It is important to distinguish this from modifications made only to somatic (body) cells, such as those sometimes targeted in human gene therapy. Modifications to somatic cells do not affect the germ line and are therefore not passed on to offspring. For a transgene to be inherited, it must be present in the germ line—the cells that give rise to eggs or sperm—ensuring that the genetic alteration is carried forward to the next generation.3