God first revealed the law of sowing and reaping when He created the natural world and every living thing to reproduce after its own kind. When he formed Adam, he breathed life into Adam from His own substance and nature. His design was perfect, and His pleasure in mankind was complete.
However, before the first natural conception let me say it this way for you millennials before Eve became Adam's baby mama. Their act of disobedience sowed the spiritual seed of sin and death into their lives and bodies. That seed produced the deadly harvest of which you and I are a part. Their offspring have been born after their own kind with the terminal disease of sin and death.
In other words, Adam and Eve had a breakdown or disconnect in their relationship with God that produced a shutdown or a defect in their stewardship in the Garden of Eden.