Can human effort break the control of our old Adamic nature?
No. Human effort cannot break the control of the old Adamic nature; only the power of God can. Even good parenting and godly homes can teach inhibitions to a degree, but every person still eventually yields. Deliverance comes only as Adam is crucified with Christ, producing new life.
Les teaches that no human endeavor can break the control of the old Adamic nature; only the power of God can do it, and we cannot do it ourselves. He acknowledges that to a degree good parents and a godly home can teach children certain inhibitions and behaviors, but there still comes a point in the best person's life when they give in to old Adam's control. The only way out from under that control is for Adam to die and be crucified. That is what Scripture teaches: God, in a substitutionary manner, died my death and your death in your place. Les then points to Paul in Galatians 2:20—'I am crucified with Christ: nevertheless I live; yet not I, but Christ liveth in me'—as the new life, the new creation spoken of in 2 Corinthians chapter 5.