In this case, lying manifests itself from the earliest of days. Children sin because they are sinners. J.C. Ryle says, Remember, children are born with a decided bias toward evil. And therefore if you let them choose for themselves they are certain to choose wrong. It is natural for us to do wrong.
Foolishness is bound up in the heart of a child.
A child left to himself will bring his mother to shame. So the name of the problem is foolishness, sin, wickedness. The Extent of the Problem Solomon is talking about any child. He is talking about my child, he is talking about your child. Paul, in Romans 3, makes it very clear that there is none righteous, no not one.