This is no longer a controversy. His birth certificate has been produced.
Secondly this was always a Republican partisan issue. If he had not been born in the U.S. this would have been "discovered" while he was a U.S. Senator. In the U.S. it's very common for the opposition party of a president to try and find something or anything that will keep the president on the defensive or pre-occupied in hopes of him or her being impeached or appear unqualified to be re-elected.
Nobody in congress who has gone through the highest of security clearances themselves really believes Obama was not born in the U.S. When Bush was president his National Guard service was in question. There were multiple scandals for Bill Clinton.
Politics is a dirty game in the U.S. and you can't believe half of what is "reported" by people in the opposition party especially during campaigns. If someone doesn't like you they'll believe every bad thing said about you. Not many research facts. As the old adage goes:
"If you tell a lie often enough it becomes the truth."