1/3 of this, 1/4 of that, 3/4 of the other. People are people and I hate to hear them being referred to like slices of pizza. If someone is going to be racist to you, they would ask if your grandfather was Swiss before insulting you.
I do think that the many cultures that are part of the child's life should be celebrated. But IMO referring to a child or adult as anything less than a whole person is insulting.