Cells in your hair follicles produce the protein keratin, which is a primary component of hair. cells in your liver do not produce keratin. why does this specialization occur?

Specialization occur to allow cells to perform different function with in a body.

Explanation:

Cell specialization is a process which modifies the newly formed cells structurally to perform their specific functions efficiently and effectively.

In order to carry out different bodily functions, the cell specialization and differentiation is necessary.  

For example – Red blood cells have hemoglobin  which process the oxygen taken in during the process of respiration, the cells in hair follicle are able to produce keratin, cells in stomach produces digestive enzymes which are able to digest food etc.