I was starting to miss you, DM!
Being the Supreme Court has never directly addressed this issue of who is a natural-born citizen, historical opinion is going to support the view that a natural-born citizen is defined as a person who is entitled to US citizenship, under Constitutional laws of the United States, at birth or by birth by one US citizen born abroad who has met the US residency requirements.
Note that Senator Ted Cruz is arguing that he is a natural-born citizen because his mother was an American citizen. His father is now a naturalized citizen.
A naturalized citizen is a foreigner, Ted's father, who takes steps to become a citizen. Ted Cruz did not ever have to take these steps to become a citizen of this country, because his mother was a United States citizen.
CNN states he is eligible, but I would suspect if he threw his hat in the ring, they would reverse that stand for a distraction during the election cycle.