There isn’t a “gene” of any enneagram type, the genes would be traits like reactivity, sensitivity, introversion, extroversion, constricted effect, obsessive focus, etc..
The enneagram type is a symbolism of traits and nothing more. Each type has a set of these traits, and the traits inherited or that have potential to forum (just like a plant that has chemotypes) are the types that will become. I see everything as a parallel and symbol, and the plants with chemotypes show human psyches also have potential to develop a trait based on environment.