Rom 5:15 But the free gift is not like the offense. For if by the one man’s offense many died, much more the grace of God and the gift by the grace of the one Man, Jesus Christ, abounded to many.

The offense is the transgression of Adam.
His sinful nature has passed to all people through all ages.
You do not need to do anything to have it.
You do not need to teach sin to your children. They will just do it on their own.
Adam died and sin permeated all mankind.
Jesus died to end sin for all mankind.
He came and reconciled what Adam had done.
But the free gift is not like the offense.
The offense is automatic – you will sin and you will die in sin.
The free gift must be taken – with it you put sin to death and live eternally.
But you must accept Jesus as your Savior.