Yeah, someone just told me that the rule is, you have the choice to play for any one of these national sides:
1. The place where you were born
2. The place where your mother was born
3. The place where your father was born
As soon as you have made your choice and you play in a senior level (over 21) national match, then you can't change sides again.
This is wrong. If you're a naturalized citizen of a country you can play for their national team. For example if someone is born in Portugal and his parents were born in Spain but then they moved to France and they became naturalized citizens, he is eligible to play for the French national team.
Indeed. If one was born in, say, France but his parents or grandparents were from Senegal and the player can acquire both French and Senegalese citizenship (obtaining a valid passport is a must before one can even play international games!) then he can play for either France or Senegal at senior level after notifying FIFA of course.
Frederic Kanoute was born to immigrant parents from Mali in France, played for France at junior levels but decided to represent Mali at senior after getting a Mali passport sorted because of his heritage.
Germany's striker Cacau was born and raised in Brazil, he moved a few years back to Germany to play football. Was never called up by Brazil for any junior or senior international games, applied for German passport/citizenship after consistently staying and playing in Germany for at least 5 years, and was eligible to play for Germany and is now in the World Cup squad.
That said, many countries do not allow multiple citizenships unless there is special cases or if countries have agreements recognising dual citizenships of each other for their citizens. For example countries like Norway, India, Japan, Denmark, Germany etc do not allow its citizens to obtain another country's nationality. I am not sure if Kevin-Prince Boateng's German citizenship has been revoked because Germany only allows multiple citizenship in special circumstances and the fact that he is also married to a German.
Lets say a Norwegian player who has never played senior internationals finds out he can get an Egyptian passport from either of his parents/grandparents. For him to play for Egypt, he will have to get an his Egyptian passport arranged, and if the Norwegian authorities find out they will have to revoke his Norwegian citizenship as a result of him becoming an Egyptian citizen.
Topic: The Official World Cup Thread