They say a lie is the only defensive weapon of a child. Not only does a child not have the physical strength to defend himself, he has not yet developed the intellectual strengths to justify himself, whether right or wrong.
I have often thought of the habit of lying in adults to be a mark of immaturity. Their lies may be more complex since they have more fully developed their intellect, but contrary to their intelligence, their emotional development has been retarded or has ceased altogether. My theory is that such development becomes impaired during their late adolescence when sin, serious sin, becomes a possibility.If they fail to repent from such mistakes, fully and soon, all other aspects of emotional maturity cease to develop. They have no other way to justify such sin except through a lie (to themselves and others), and since their intellect is not quite set, the habit of lying gets ingrained.
Examples abound within public figures where we say, “I can’t believe he thought he could get away with that lie.” He may be very intelligent, even brilliant, but he is morally stuck with the self-preservation paradigm of a little child.