To be fair, there is a clear definition of ethnicity as "the quality or fact of belonging to a population group or subgroup made up of people who share a common

To be fair, there is a clear definition of ethnicity as "the quality or fact of belonging to a population group or subgroup made up of people who share a common cultural background or descent". So while an individual cannot decide who they descended from, they can choose whether or not to accept a set of cultural norms. People routinely change religions, learn other languages, or follow other traditions outside the ethnic cultural norms they were born into. The TFA states that ethnicity is only one of many potential "population descriptors" and recommends that researchers "use multiple descriptors rather than a single, overly broad category".