I don’t think it’s so uncommon to have more than two citizenships. My son has a friend with three: U.S.A. (by birth), Canada (through her father, who’s from Montreal), and Brazil (through her mother, who’s from Sao Paulo). She went to college at the U. of Toronto and is now in graduate school at McGill, and has thereby saved her parents quite a bit of money. And she has a grandmother and other close relatives in Brazil, and has been able to spend a lot of time there.
My son and I will both have two citizenships fairly soon: the U.S.A. (by birth), and Germany – me through my mother and her parents, and my son through me, based on Article 116(2) of the German Basic Law, which provides for restoration of citizenship to former German citizens who between January 30, 1933, and May 8, 1945, were deprived of their German citizenship on political, racial, or religious grounds, and to their descendants. See http://www.germany.info/Vertretung/usa/en/05__Legal/02__Directory__Services/02__Citizenship/__Restored.html and http://www.uk.diplo.de/contentblob/4235518/Daten/4289717/CitizenshipReobtainingGermancitizenship.pdf. We put in our applications about a year ago (together with the extensive documentation required to prove eligibility), but given the backlog resulting from the large numbers of applicants, it can take at least a year and a half sometimes.
This was not something that I ever felt particularly compelled to do, although I find it somewhat meaningful symbolically as the restoration of something both my mother and her parents were deprived of for the sole reason that they were Jewish. It’s the least that Germany can do after what happened to my mother, her parents, and their family, although obviously nothing will ever make up for that. And it does give me options should I ever decide that I need to leave this country. Not that that’s very likely to happen, but one never knows. But having German – and thereby EU – citizenship will potentially benefit my son in all sorts of practical ways that are far more likely to occur, by allowing him to live, study, and work in Germany and elsewhere in the EU without restriction should he ever choose to do so. (He is already quite proficient in German, and has spent several months each in Germany and Austria.) .