Clow Reed is the one who had a British dad and an Asian mother... Eriol is the reincanation of CR. In the managa, Eriol had no partents, as CR died he split in half. One half was Sakura father, Fujitaka and the other was Eriol. In the anime it is never made clear as Sakura's father isn't a part of CR, only Eriol is. One can only persume that Eriol is just full British or had only one parent, CR himself.