Non-starter. If one has it, one cannot be "adopted out" of US citizenship.
The issues we need to be pushing is the definition of natural born citizen, and his parents, one an American the other a British Subject. Nobody disputes that fact.
No one disputes it, least of all Barack Hussein Obama, Jr., who admitted in Bill Ayer's best-seller "Dreams of My Father," that he was born a dual citizen. However, Team Obama has had great success in conflating "Native Born," with "Natural Born." Frankly, it's one of the greatest PR Coups of all time. Of course, it's based on birth in Hawaii, which although possible, remains unproven.
Not calling "foul," in the 2008 election is the greatest failure in the Republican Party's 175-year history. However, it is not too late for one state legislature or Governor to refuse The Mombasa Moonbeam a place on that state's ballot in 2012. The concept of "Natural Born" citizenship is already plenty well-enough defined for that. That strategy has the benefit of a quicker SCOTUS review.
You said, “If one has it, one cannot be “adopted out” of US citizenship.”
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Can one be “adopted into” natural born citizenship?
Also, one can make an affirmative act after the age of majority that removes one’s eligibility to be POTUS.