Hello Myriam .
There is no intended racism in the query about your ethnic background .
Yet there is a difference between your nationality (your country of origin ) and your ethnic background .
For example you might be born in Chile or Columbia and your ethnic background would be Hispo american. You might be born in Tunisia and your ethnic background is Arab African.
You might be a Chinese born in china and your ethnic background is Asian .You might be born in Kenya and your ethnic background is Black African.
You could check this detailed definition of ethnicity :http://en.wikipedia.org/wiki/Ethnic_group
to better understand what it really refers to ,because the concept is a bit complex .To determine your ethnicity could be built on shared cultural , geographical , religious, linguistic traits ,some or all of them ,so it is a bit vague .