You know, unless both of one's parents are full-blooded of their respective races, one can't really say for certain how much of each race they are. You do get exactly 1/2 of your genes from each of your parents, but you only get 1/4 -on average- from each grandparent, because there's nothing in your parents' genes that marks which parent it came from. So theoretically you could get all or none or some of your paternal/maternal genes from one or the other grandparent. Though, all this is talking about 'race' as a genetic concept, but most geneticists will tell you that 'race' isn't a very useful or well-defined concept in the first place.
