Actually,
Sec. 349. [8 U.S.C. 1481]
(a) A person who is a national of the United States whether by birth or naturalization, shall lose his nationality by voluntarily performing any of the following acts with the intention of relinquishing United States nationality-
(1) obtaining naturalization in a foreign state upon his own application or upon an application filed by a duly authorized agent, after having attained the age of eighteen years;
Barry Soetoro, Indonesian National born in Honolulu, naturalized as a Indonesian. When his mother amended her US Passport she told the US State Department she intended on staying in Indonesia indefinitely. That’s enough information for the SoS to issue a Certificate of Loss of Nationality.
The State Department provides for a minor issued a Certificate of Loss of Nationality an opportunity to recapture their U.S. Citizenship until 6 months after their 18th birthday.
Obama naturalized as a U.S. Citizen in 1983.