That's not spelled out in the Constitution. It's an obscure legal theory which would require a Supreme Court decision to resolve. It's never come up, and given the precedent of the 2008 election, if it ever does, expect it to turn out the same way: natural born == citizen by birth. Had Obama hidden his parentage, it might be different. But, far from hiding the fact, he wrote passed off as his own work a ghost-written autobiography on the topic and made a nice pile of royalties, which are still rolling in. Indeed, that book and the legend it created is the reason we heard about the guy in the first place.
To hope to oust Obama via the courts is an exercise in futility. Going forward, the best hope would be a new amendment, the primary purpose of which would be solve the anchor baby problem. If such an amendment were properly written, it might also work in an unambiguous definition of natural born
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Actually it is. The Constitution was established by "we the people of the United States" for "ourselves and our posterity." IOW, those who formed the Constitution were the original citizens and their children were the country's natural born citizens. The country was not established for ourselves and "whoever was visiting and happened to pop a baby on U.S. soil."