"But a better analogy for genes might be a script for a theater production or film. Our genes are like the script, and the exposome and epigenome are like the production and performance. The script of Romeo and Juliet doesn't change from one production to the next, but how it is produced and performed can vary dramatically depending on the director, cast, crew, set design, costumes, and other factors. If a script is terrible, even a great performance can't save it. On the other hand, the best script in the world won't matter with a terrible production. "