[RKV]

The Irish tripped to this problem in 2004 when they passed a referendum requiring that at least one parent of a child born after enactment had to be Irish or eligible to be Irish in order for a child born in their country to have birth citizenship. The vote was not even close. It became the Twenty-seventh Amendment of the Constitution of Ireland by an 80% majority.

http://www.ireland.com/focus/referendum2004/guide.html

[Dutch Boy]

That is an interesting why of handling it. It would also solve many other problems.