Tough one, but I'm going with CRaP...
His grandmother Marie-Cessette Dumas, a slave of Afro-Caribbean ancestry. It is not known whether she was born in Saint-Domingue or in Africa (although the fact that she had a French surname probably means that she was Creole), nor is it known from which African people her ancestors came.
The game may go either way, depending on their definition of African.