That is your opinion, not a fact. Obama is in the WH and holds a US passport. He has never been naturalized. Even if born in Kenya, his mother was a US citizen. And the state of Hawaii says he we was born there.
Ted Cruz was born in Canada and was a Canadian at birth. His mother was an American but his father was Cuban who became naturalized in 2005. The Cruz situation is not that much different than Obama.
Every president to date was either a citizen at the adoption of the Constitution in 1789 or born in the United States; of those in the latter group, every president except two (Chester A. Arthur and Barack Obama) had two U.S.-citizen parents. Both were controversial at the time. Cruz will invoke a similar controversy, which is why we need SCOTUS to adjudicate it now.