What about multi-generaltional requirements, like "one of your parents must have been born here"? Also, it gets complex when discussing illegal immigration. Wh

What about multi-generaltional requirements, like "one of your parents must have been born here"? Also, it gets complex when discussing illegal immigration. What if an immigrant is laying low for an extended time? Is it different if the host country looks the other way and doesn't really enforce the laws, because some sectors benefit from the cheaper labor?