Thieves and Liars, Liars and Thieves

What makes people steal?  

You can read all kinds of research where they try to explain the psychological reasons for stealing.  Some of it is interesting and may be right:  

"Stealing becomes an issue when the person doing the stealing is old enough to know better. Sometimes children under the age of five take objects that interest them, not yet understanding that stealing is wrong. They might not have enough self-control to resist taking something they want.
For those old enough to know better, there are several reasons for stealing. Stealing may be caused by jealousy, low self-esteem, or peer-pressure. Social issues like feeling excluded or overlooked can also cause stealing. People may steal to prove their independence, to act out against family or friends, or because they do not respect others or themselves,
Sometimes, stealing is a compulsive disorder. This is called kleptomania. In other cases, a person may have come to believe that stealing is socially acceptable. Some people steal as a means to survive due to economic hardship. Others simply enjoy the rush of stealing, or steal to fill an emotional or physical void in their lives."
http://www.healthline.com/health/stealing#Overview1 

 There is an interesting article on Forbes about stealing:
"The research suggests something telling about how we rationalize behavior given changing circumstances: moral behavior shifts when moral standards shift, and we’re chronically unaware of how frequently we shift our moral standards.  Even brief financial deprivation—or the perception of it—can trigger a shift in moral standards.
Alter calls this a shift to “transient ‘new’ moral standards,” and we’re lighting fast at coming up with reasons to justify the shift, even while we’re likely to criticize someone else for doing the same thing.
It’s this human proneness to shifting moral standards that makes deciphering the motivations of questionable behavior less than crystal clear.  Very seldom do regular people—those not sporting a criminal rap sheet—do something “just because they could.” Our justifying brains are busy working out a skewed calculus to rationalize our behavior even if we’re not consciously thinking it through."
Whether Rich Or Poor, Feeling Deprived Makes Us Steal More

What do I think causes a person to steal?  I think some people are just outright low life scum with no morals or conscience.  And from some recent personal experience, that Thieves and Liars tend to go hand in hand.