Yes all but one, the firstborn of the dead, are adopted. They are adopted when they receive the Holy Spirit.
Faith in Christ:
1. Repent
2. Be baptized for remission of sin
3. Receive the Holy Spirit
Romans 8:15
“For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, ‘Abba! Father!’
Prior to that they are children of their parents.
John 1:12-13
12 But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name: 13 Which were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God.