That depends on:
1. Where he was actually born (HI or Kenya)
2. Whether his parents HI marriage was legal in Kenya
If he was born in Kenya, his Kenya citizenship hasn't expired and he may not be a US citizen.
If his parents marriage was bigamous, then the British Nationality Act of 1948 explicitly did not apply to any illegitimate children of BHO Sr. and would not make BHO II a dual citizen subject of the Queen, but only a unitary USA citizen of a single mother. Note that the clever statement released by Obama said that the BNA of 1948 “governed the status” of his children. The BNA of 1948 itself says it includes only legitimate children at birth as UK subjects.
A woman, Kezia in Kenya, claims to have been the first tribal wife of BHO Sr. Tribal marriages are legal in Kenya and bigamy was not, at least under the UK Kenya Colony law even for Muslims per Kenya Marriage Act 1902.
Stuff I’ve read lately says that very possibly Kezia was not married to 0bama Sr anyway.
And also that perhaps SADO and 0 Sr if married, may have married in Kenya. Her whereabouts are unknown for months and months anyway.
The whole thing is so dark and tangled.