Ron Weasley has another sibling?

*it was a 'normal day' in the great hall (let's be honest, with the golden trio. There is no such thing). When Ron accidently let it slip during a discussion with his friends* Hermione: *studying advanced transfiguration* Harry: "Ron, how many siblings do you have again?" Ron: "Well there's Ginny, me, Fred, George, Percy, Billy, Charlie and-" *Ron stops himself realising he was about to say (your name)* Harry: "And?" *leans forwards intriguied* Hermione: *looks up from her book* "Ron, you've only told us you had seven of you, including yourself. What do you mean and?" Ron: "I mean we count Scabbers as family!" *Ron stuffs his mouth with food so he doesn't have to answer. But Hermione presses on with curiosity and determination* Hermione: "Who are they?" Ron: "Fine... fine, we have a younger sibling apart from Ginny" *he relents*