If a chiled born out of country to an American father is an American citizen, likewise a child born out of country to a Cuban father is a Cuban citizen.
If Canada has birthright citizenship, Ted Cruz can legally owe allegiance to Canada, Cuba and America.
Not sure how you can classify him as a “natural born” American citizen.
Cruz has an American birth certificate, not a Canadian one, but if he did, he could drop the Canadian one and then have allegiance only to America. You can only have allegiance to America to run for president. He doesn't have a Canadian or Cuban birth certificate so he can't claim allegiance to either of those countries.
I go back to my grandson. He has dual citizenship, English and American. He cannot have allegiance to America due to being an English citizen. Neither can he claim allegiance to England since he is also an American citizen. To claim allegiance to either country, he would have to give up the other citizenship.