Like the others said, being a mix up he is a moggie (domestic shorthair if you want to be courtesy), with not much of russian blue, save the big ears. Compare with the grandmother! (yes, she is of european type, even a good scandinavian type)
However, I want to mention russian blue mix-ups are quite often black, sometimes with some white spot. Probably because the blue-grey color in them is a dilute black. Thus it doesnt need much to reinforce - is my theory.
So I can accept he has some russian background in her.