The big question is when do people become native. You can't go back 200 years for obvious reasons, if you're born in America you're and American, just because your grandfather was born in Belfast it doesn't make you Irish. If you moved to Belfast when you were 10 and have lived there for 30 years though, then you clearly are.
Northern Cyprus is what it is now. Yes there were issues 50 years ago when it was partitioned, but life moves on. On the other hand if the US had invaded Basra, displaced the population, put in 2 million of its own citizens, and then claimed independence 2 months later based on overwhelming support, that wouldn't be reasonable. 100 years later, then sure.
Sometimes people lose out. It's sad, and shouldn't have happened, but after some time (that might be 10 years, it might be 100) you have just as much right to your voice as everyone else living there.