An embryo expands by cell division, making an exact replica of itself with all the same DNA, the same genes. But in the adult body, the cells are differentiated as to their functions.
... The proteins a cell makes determine cellular function; the genes have the code to make the proteins. ... But the source of the programs is not part of the DNA.
... Rupert Sheldrake (1981) has shown how nonlocal and nonphysical morphogenic fields are essential to understand biological form-making from the one-celled embryo. The instructions of form-making, cell-differentiation (all cells contain the same genes, yet toe cell genes are activated very differently from brain cell genes), are nowhere to be found in the physical body, and that includes the genes (which are more or less instructions for protein-making).