John 1:12-13 — 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:
Which were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God.
Verse 11 is referring to Israel, so verse 12 must be too. It applies to Gentiles by application, but refers to the Jews.
received = accepted
power = right, authority. God, and He alone, can give it.
Paul explains the believers' sonship, but John only refers to the "children of God."
Believers become children of God by the action of the Holy Spirit based on faith in Christ — NOT by inheritance (blood) or works (will of the flesh) or the aid of another person such as a priest or the rites of a church (will of man).
children — from "to give birth"