Imprinting is a process that happens beyond genetics, and is therefore called epigenetic. An epigenetic event can change the expression of a cell’s gene without changing the basic genetic code. During imprinting, one or more molecules are added to the gene, acting as a stop code. These molecules tag the DNA and prevent it from being transcribed into proteins, therefore blocking the expression of that gene.
It really is an excellent book, just not exactly easy material so I haven’t had the energy for it recently. I’ll get back to it yet! Definitely one of my all time favorites though