Perfect time to get this sentence, with the release of the song: shevet achim ve'achatot !!: https://www.israellycool.com/2019/04/21/watch-a-tribe-of-brothers-and-sisters/
Brothers (אחים) could also be translated as siblings, but not sisters (אחיות). So the two together wouldn't be siblings.
Edit: (3/5/17) I would agree that "אחים ואחיות" could be translated as "siblings." I still think that "brothers and sisters" is the better translation, but "siblings" makes sense. I guess I must have felt differently eight months ago! ;) Although, with a lot of masculine plural pronouns it includes more than just the masculine. For instance, "ילדים" can mean both "boys" and "children." So it would makes sense to assume that "אחים" could mean both "brothers" and "siblings."