Here is the Constitutional proof (via PH) that neither Marco Rubio nor Ted Cruz is eligible to be in Congress, much less the Presidency.
Here is part of Vattel’s discussion of law.
“The citizens are the members of the civil society: bound to this society by certain duties, and subject to its authority, they equally participate in its advantages. The natives, or natural-born citizens, are those born in the country, of parents who are citizens. As the society cannot exist and perpetuate itself otherwise than by the children of the citizens, those children naturally follow the condition of their fathers, and succeed to  all their rights. The society is supposed to desire this, in consequence of what it owes to its own preservation; and it is presumed, as matter of course, that each citizen, on entering into society, reserves to his children the right of becoming members of it. The country of the fathers is therefore that of the children; and these become true citizens merely by their tacit consent. We shall soon see, whether, on their coming to the years of discretion, they may renounce their right, and what they owe to the society in which they were born. I say, that, in order to be of the country, it is necessary that a person be born of a father who is a citizen; for if he is born there of a foreigner, it will be only the place of his birth, and not his country. ”
Here are the links to the Exhibits:
http://oll.libertyfund.org/titles/2246#lfVattel_label_1642 See Sections 212-217