To curiosity:
First, you are assuming that Obama was a US citizen before his adoption. We do not know that for a fact, since he's never shown us a bona fide long form birth certificate nor any other credible evidence to show that he was a US citizen at any point in his life. All the documents he has shown us are likely forgeries.
Secondly, the constitution requires that a president be a natural born citizen. To be a natural born citizen, he cannot have had dual citizenship at any point in his life. So citizenship of Indonesia, even if he had American citizenship simultaneous to it, would make him constitutionally ineligible for the presidency.
The reason for the "natural born citizen" requirement for president in the Constitution is to assure that the chief executive officer of United States government has never had any loyalty or allegiance to any foreign country.
Sorry, curiosity, the United States offers some wonderful opportunities for foreigners coming here, but the presidency of the country is not among them.
S/he isn’t that curious.