There is often a selection of ‘more than one’. I would choose that.
You are correct, Hispanic is a culture. The odd thing is that for the rationale used by colleges, being ‘different’ or mistaken for a minority would give you some of the disadvantages of having grown up in that minority. With the cultural shift toward identifying as whatever you want, you could reasonably make the argument that you are Russian, but identify as [fill in the blank]. 