so if some crazy nation has a consciption law that allows going 10 generations back it would disqualify someone?
Do you know of such a nation? Are you just trying to argumentative? There are nations that will grant automatic citizenship to the descendents of that Nation's citizens. Ireland, Italy, and Israel all have that policy, but I know of no nation which would actually try to compel an American to become one of their citizens.
Offering someone the opportunity to be one of their citizens is not at all the same thing as having a legitimate and recognized legal claim on their citizenship. Do you have any idea how many nations recognize citizenship through paternity?
I have read accounts of French Citizens who happened to be born on British Soil, being arrested and charged with Treason because they refused to fight in an English War against France. French Law made them French, while British Law made them British. This is the sort of loyalty problems that our founders wished to avoid in the Presidency.