We know Blaine has Cooper for an older brother, but lots of the other Gleeks also have siblings. Santana has a (rumored) older brother, and Mercedes also has a college-age older brother whose room Quinn used in season one. We know Quinn has an older sister whose married, and Puck has a younger sister and a (rumored) younger brother as well. Brittany has a younger sister and (I think--correct me if I'm wrong!) a younger brother as well. And we've actually met Sam's siblings, the younger twins, in Rumours. Kurt and Finn were only children, but they're kind of stuck with each other now.

We don't know if Artie, Tina, Mike, Sugar, and Joe have siblings or not.

But we do know that Rachel's an only child, to the point where she even sang an original song about it.

Discuss?