The fact that you assume someone knowing the MC is from a Spanish speaking family would imply you want the MC to be Hispanic shows you know that information would influence a player into making a Hispanic MC. Note that I didn't say that anywhere in my comment.
I Can't do anything I want with my MC because canon information like them being from a Spanish speaking family exists. I could keep the Korean name and headcanon that they're adopted, but I can't play as them being from a Korean family. And that's a good thing if I was informed of it.
People make MCs based on some unchangeable facts the story provides of them. Those are part of a basic premise. The premise is already set. Informing people of the premise doesn't "force" them to do anything they aren't already forced to.
(This is "I", btw. From your server, if you remember.)