There's no such word. You have to say brother and sister or something like that.
Well, I actually found words суродженики and сібси in Wikipedia, but this are not the words we use in our daily lives, maybe only doctors would use it in their professional activities
Суродженики is quite interesting word. What is its etymology? I mean I find this word is a combination of three words с+урод+ жденики. Further I guess C means with, Урод means stomach and жденики means living together ! can anybody throw light ?
I would rather connect it to the Ukrainian рід (-род-), which is a common Slavic root for words related to birth, kinship and harvest. From that, you get уродитися (a rather specific verb for "to be born" used to characterize the thing or person born). Then, уродженець "a native".
Cпасибі. This may be possible, But does the words Рідб уродитися exists in Ukrainian or any other Slavic languages? Or are they reconstructed words?