It was noted in the text that the genetic "code" is best thought of as written in

The answer is erasable pencil. In the text, the genetic code as sketched in erasable pencil rather than indelible ink. The reason behind this is that gene expression can be changed, starting prenatally all the way through the lifespan, and sometimes in lasting ways by environmental factors. Genes do not conclude anything. Rather, genes and environment work together and co-act to persuade gene expression and in-turn, development and behavior throughout the life span.