If all our cells have the same genetic make-up, how does one become a kidney cell and another a bone?

How do the different regions of our bodies develop?If all our cells have the same genetic make-up, how does one become a kidney cell and another a bone?
Good question. The cells are only identical for a short while and these are called stem cells. They differentiate a few days after fertilisation and turn into the various tissue types.If all our cells have the same genetic make-up, how does one become a kidney cell and another a bone?
What Peter said is correct but its what ';bits'; of the cell are turned ';on and off'; which determines what type of cell they are.