This is for a short story idea.
Is it possible to modify the DNA of a child to make their metabolism more susceptible (physical response, addiction, etc) to a certain type of chemical i.e. a chemical present in a fictional food. The idea being that their DNA is modified when in the womb (or before) and when they grow older (think teenager) they become addicted to said product.
This could be before conception, during pregnancy or after birth. What ways, in the future, could we go about doing this? Maybe chemical mutagens (http://en.wikipedia.org/wiki/Mutagen) or site-directed mutagenesis (http://en.wikipedia.org/wiki/Site-directed_mutagenesis)? Gene therapy?
Or is there a way to alter the regulation of the physiological processes in the human body to make someone become easily addicted to a particular product?
I'm looking to have this aspect of the story as scientifically accurate as possible so I can examine the ethical questions around it within the story.