Our laws are based on English laws in every state but Louisiana, which is based on Napoleonic law. The British considered any children born to an English citizen to be a British subject no matter where they were born, and even if only one of the parents was an English subject. Our founding fathers held similar views, and they would have considered Cruz as a natural born citizen since his mother was an American natural born citizen.
http://powderedwigsociety.com/eligibility-of-cruz-and-rubio/#
Pretty powerful and easy to understand presentation about Cruz and Rubio’s eligibility to run for POTUS.