How can cells have the same DNA?

Although all calls have the DNA only some parts of it are turned on different cells (this is called gene expression). Which genes of the DNA are turned on determine the functions and kinds of cell. Even in the same kinds of cell genes can be differently expessed depending on what the cell needs to do at the time. If you have a drink of alcohol for instance a whole bunch of genes turn on in the liver to detoxify the alcohol. When you have meal hundreds of genes in the stomach, intestine and blood stream kick into action to digest the food and send it away for storage or immediate use. Cells have many things that regulate gene expression some things turn genes off or down others turn them up or on. There are factors turn on whole cascades of genes.