I haven't read all the replies but something jumped out to me. Adam and Eve sinned in the garden. Whether they were set up to fail or not
Is a baby sinning by reaching for a toy, or crawling off of a blanket? It seems to me the parents are setting themselves up to define sin as whatever they don't like and creating a crime where there is none
A baby is exploring, as he was designed to do. Exploring the worls around you is not sin.