There are a lot of emigrants all over the world. it happens for all the reasons (war, money, etc). I was a exchange student near LA (98-99) and I opted to attend Hollywood High (bad choice!) over there I thnik that 70% of the students were imigrants (latinos, russians, armenians, southeast asians) but they lived like americans, payed taxes like every other american, learned american culture. So guys like this could choose to represent USA (because he lives there), Armenia (because he was born there) and lets suppose that this fellow parents were from Ukraine, he could also play for Ukraine. This is based on International Laws. If a british couple has a child in Brazil, the kid is Britsh AND Brazilian if they go to Argentina and live 18 years over there he can be an argentinean too.
About the Netherlands case, Suriname has great bounds, it's one of the 3 countries (the others being Guiana and French Guiana) that we learn at school that they are part of south america only phisically, those three countries are very dependable on the countries that they were colonies.
To finish it, Kariya, Gretzky, Iginla, etc are all son of imigrants. Rob Regehr was born at the same city that I was born and live now. And all those guys are stars playing for team Canada.
P.S. I know that there are a few cases that doesn't make sense (Deco maybe one, although he has a Portuguese heritage) but most of the cases exposed here are commom.