You are avoiding my question. How can an infant sin?
SIN
SIN (Heb. hatta'a; Grk. hamartia, a falling away from or missing the right path). Also numerous other Heb. words.
General. The underlying idea of sin is that of law and of a lawgiver. The lawgiver is God. Hence sin is everything in the disposition and purpose and conduct of God's moral creatures that is contrary to the expressed will of God (Romans 3:20; 4:15; 7:7; James 4:12,17).
(from The New Unger's Bible Dictionary. Originally published by Moody Press of Chicago, Illinois. Copyright (c) 1988.)
You posted:
God declared children free of guilt from their father's sin in the OT. Not from their own sin.
So what you are saying is God declared children are free of their father's sins but not the sin of Adam? Isn't that contradictory, since Adam is the father of all mankind?