Os genes codificam proteínas “RNA”, eles não são exactamente uma identidade molecular entre duas células, até porque cada gene tem dois alelos.

A gene is a unit of heredity in a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism
Living things depend on genes, as they specify all proteins and functional RNA chains. Genes hold the information to build and maintain an organism's cells and pass genetic traits to offspring, although some organelles (e.g. mitochondria) are self-replicating and are not coded for by the organism's DNA.

"All the cells in your body have the same genes, but they don't all make the same proteins," said Chang, MD, PhD, who is also a Howard Hughes Medical Institute Early Career Scientist.