How recently must a person's ancestors have migrated from one country to another for that person to be able to prefix his or her nationality with the adjective of the country or continent his or her ancestor emigrated from?
Apparently, a person who can claim they are something-something is a lot more special than a person who cannot; at least the way they go on about it indicates that they certainly think they are. In fact, I feel decidedly uninteresting because of the fact that I have only ever referred to myself as English.
However, perhaps I am not so culturally boring. My DNA shows that an ancestor of mine emigrated from the Fertile Crescent to near Royston in England about seven thousand years ago bringing the concept of farming with him. Does this mean I can legitimately refer to myself as Mesopotamian-English and be as important as all those who already have double-barrelled nationalities?
It is very important that we all know exactly where our ancestors came from so that we can get upset about the correct things. If I am Mesopotamian-English I would be obliged to become irate if some upstart Romano-Celt from up the road started ploughing his fields in a Mesopotamian way. Such blatant cultural appropriation is just not on.