He is Scottish, but his family fled to the country from Rwanda.
Doctor Who has never been Black before - OK technically not true - Jo Martin was revealed as a previous incarnation, "the Fugitive Doctor," that the "current" Doctor (Jodie) was unaware of as the "Timeless Child")
Of course, there are some rumors Rusell T. Davies might retcon all the Timeless Child changes, which I don't know whether that removes Jo Martin from the 'continuity' or not.
BTW, there are also rumors that in Jodie's final episode, the 60th Anniversary, she and Yaz will share the Doctor's first same sex kiss (Yaz already confessed feelings for her.)
