Are Christians children or brethren of Jesus?

I noticed the hymn *Redeemed* states the following in its chorus (emphasis added): > Redeemed, redeemed, > > Redeemed by the blood of **the Lamb**; > > Redeemed, redeemed, > > **His child**, and forever, **I am**. This chorus appears to state that Christians are children of "the Lamb," (i.e., Jesus). However, doesn't Hebrews 2:11-12 portray Jesus as considering Christians His *brethren* rather than children? Alternatively, might verse 13 involve us being called Jesus's children? Maybe Isaiah 9:6, which refers to the Messiah as "everlasting Father," supports this as well. According to the Bible, are Christians brethren of Jesus, children of Jesus, or both?