Somatic gene transfer involves adding genes to cells other than egg or sperm cells. If you had a lung disease caused by a defective gene, scientists might be able to add a healthy gene to your lung cells and alleviate the disease. The new gene would not be passed to any children you may subsequently have.
The desired gene is attached to a viral vector, which has the ability to carry the gene across the cell membrane.
Clinical trials of somatic gene transfers have been underway since 1991. These attempts at somatic gene therapy have so far produced very few successes and a number of serious adverse results, including deaths.
But somatic gene transfer may eventually become an effective treatment for at least some important medical conditions. Somatic gene therapy should be evaluated according to the same criteria as other medical procedures: safety, efficacy, accessibility, and social implications.
However, somatic gene transfer techniques might also be proposed for "enhancement" purposes. Some of these might be inconsequential but others could be unacceptable and would need to be proscribed.