Coupled with no known action of Barry renouncing his born with allegiance to the crown...he continues to be British to this day (see Blackstone).
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Thank you BP2 for all your great info...
When I became a US citizen in 1975, I had to renounce my New Zealand citizenship...
I had to actually raise my right hand and swear that I renounced my alleigence...
Until I did that I could not be sworn in as a US citizen...
I did that during my vetting apointment, one month before the swearing in for US citizenship ceremony...
Barry Donham would have been about 14 at that time ...
Unless the law changed since, and as there is no proof he ever renounced his Kenyan/Indonesian citiezenship when he came of age, then he is not a US citizen...
If he was a citizen before, then his case would be different than yours. He never would have not been a US citizen, even though he would have been a dual citizen. He never would have needed to take a citizenship oath. If he was a citizen to begin with. A child cannot renounce his/her citizenship under US law, and he was only about 10 when he returned to the US. He could have maintained any Indonesian citizenship, simply because the US did not and does not officialy recognize it. But he would have needed to travel to and from the US on a US passport, especially after turn 21, because traveling to the US on a foreign passport is one way to renounce citizenship.
For this purpose it would not matter if he was naturalized or native born (of which "natural born" is, a subset)