I'm sure we'll find out pretty early on what the story is when the new character makes an appearance, because the show isn't shy about using the phrase "mixed race." April used it, too. A Puckerman half-brother will bring some diversity back in one way or another, with religion and ethnicity.
Fans have been clamoring for Blaine to be established as "hapa." So far all that's been established is that his hair without gel is an afro. I would love to see one of Blaine's parents being Asian, to establish Blaine's race. It would probably make Will like Blaine less, but it's the other kids whose reactions I'd like to see. Did Tina and Mike know, if it turns out that Blaine is half-white/half-Asian? Mike called Tina a "self-hating Asian." What would Tina's reaction be? Blaine's been very careful not to pass for straight. It hasn't been clear if he's been trying to pass for white. It will be interesting to see what the McKinley students knew about his ethnicity and how they react.