www.privideos.com
Under the Old Covenant children were born into the Covenant without any personal choice. Their parents decided to circumcise them on the eight day, and it was up to the parents to teach them and train them in the ways of the Old Covenant. Under the New Covenant, no one in covenant has to be taught to know the Lord because only those who make the decision to follow Christ are in covenant. They are the ones who are born not of flesh but of Spirit. In the age to come/ world above, being married and being given in marriage is not necessary to produce children of God because they are born by the word of truth.
Some additional study helps:
Born of Above: https://labornotinvain.com/2016/10/27/born-of-above/
I am from Above: https://labornotinvain.com/2016/03/16/i-am-from-above/
Acts 2:39 The promise is for you and your children
Sounds like they were born into it
The promise was to the elect of God within the lost of the house of Israel and those that had been scattered first (some gentiles where included) prior to the parousia. Acts 2 is the Gospel going to Jews and the elect still had to repent, believe and be baptized because they we still under Torah so there was still a choice to be made. Grace and peace.