Why We Lie??

Why We Lie?? It's a Good Question to be asked 
The concept of honesty and integrity is an interesting and timely one, we all think of ourselves as basically honest and trustworthy people, so why do we lie? What are the things that will make an otherwise upright and honest person resort to unethical behavior or lying?
this graphic which summarizes some of the factors which will tend to increase either honesty or dishonesty.

Share with us What do you think? We people attempt to lie sometimes?