Why would Luke use an Aramaic term, when he was not a Jew, and traveled with Paul, who knew well both Aramaic and Greek? If the point was as critical to the Christian’s understanding of the Bible, why would Luke not use a more precise term, as he did for the offices of the Roman officials?
Also, where is this original Aramaic document? I know there are some Aramaic translations that post-date the earliest known Greek versions, but I have not heard of any that pre-date the Greek.
Again the Greek word does not indicate biological brotherhood for reasons that are readily explained on other sites. Moreover if you are correct why do modern greeks disagree with you? Why does every christian group that was around since before Luther disagree with you?