What are the key aspects of Stalin's personality and his personal life history that might have led him to order the Katyn massacre?

Stalin is generally considered by historians to suffer
from paranoid personality disorder. He trusted no one, and believed that anyone close to
him planned to either harm or kill him. This has been offered as an explanation of the
Great Purges (as well as the political benefit he derived from it) and the fact that
almost all persons who were close to him were ultimately disgraced and executed. As a
child, his father beat him mercilessly. He had been rejected for service in the Czarist
Army because of a number of physical defects, including the fact that one arm was
shorter than the other. These physical conditions may well have contributed to his
personality disorder. It should also be noted that Stalin was an exceptionally short
man; he never stood taller than five feet five inches his entire life. Most pictures
show him either seated, behind a podium, or standing well forward of others in the
picture to disguise his lack of height. This is another factor that might well have
contributed to the savagery which he exhibited on occasion. An excellent psychological
analysis of Stalin is contain in Donald Bullock's Hitler and Stalin; Parallel
Lives.