Not All people born in Belgium are Belgians!
It's not because you are born in Belgium that you are Belgian,
A Chinese born of Chinese parents in Nigeria is still Chinese
A Nigerian born of Nigerian parents in Sweden is still Nigerian
A Sweed born of Swedish parents in Morocco is still Swedish
A Moroccan born of Moroccan parents in Belgium is still Moroccan
A Belgian born of Belgian parents in Congo is still Belgian
it is as simpel as that!