Where in scripture do you find that? Adam and Eve were not made sinful, they made themselves so when they disobeyed God.
Adam and Eve did not make themselves .. anything. They were designed by God and were designed susceptible to temptation and sin. Apparently God did not want robots so he gave man free will which includes the ability to disobey and sin. God created everything, right? So the ability to sin was allowed in God's design for man. In addition since God is sovereign God knew in advance that man would sin. He also knew man would need a savior and sent Christ.
My issue is not with God. It's His game and He can do what he wants. We have nowhere to go except Christ and His mercy. We are not meant to know the details of how all this works right now. All we need to know right now is that we need a relationship wit Christ