Subject: How is white blood cell structure affected by intermarriage?

While having my blood tested for donating bone marrow, the phlebotomist 
told me that the structure of the white blood cell differs in different 
ethnic groups. However, he wasn't able to tell me how the white blood cell 
structure changes as different ethnic groups intermarry. Does the structure 
of the cell become modified, or is one type of structure dominant and 
another recessive (as in brown eyes being dominant over blue)?

Re: How is white blood cell structure affected by intermarriage?