Well, I must, of course, take your word for it, jansamu.
I would guess, from your use of "do you have", that you're a speaker of American English. I can only say, for my own part, and as an English-speaking resident of Britain for >65 years, that even though I know what it means I have never heard anyone say the word "sibling" in an informal, non-academic situation ...even if "brothers and sisters" is a bit of a mouthful by comparison!
"Sibling" has a relatively short history in modern English (a century or so, and only really coming into use, in academia, in the inter-war period), having been revived from Old English to translate the German "Geschwister" in such expressions as "sibling rivalry" (a calque of "Geschwisterrivalität").
However, for me to drop into casual conversation a question like "How are your siblings?" (the word sounds inherently funny, even faintly risqué) would almost certainly provoke a guffaw, and the response "My WHAT...?")
I expect it's different in America. :)