After achieveing power, Stalin asked his mother why she beat him as a child. She assured him that's why he turned out so well.
Many a retail Assistant Manager across America could tell an identical story. ;)
The notion that people are born evil is nonsense. Evil behavior stems from fear - and the only fears we are born with are the fear of falling and the fear of loud noises. Everything else is learned.
Like many poor Europeans at the time (and - as "Borat" showed us - like many backward societies in Europe and Asia still believe) Hitler learned early on to fear Jews and their "sorcerous powers" and acted dramatically to rid himself of that phobia once he got the power to do so.
Of course, Stalin's mother was a little dotty.
She didn't really understand what he did: there is a lovely story about her asking him what it was that he did. After a long fruitless explanation, he finally retreated to the explanation, "It's sort of like being the Tsar."
That sank in, and his mother replied, "Too bad, it would have been better if you'd been a priest."
According to Radzhinsky's bio, Stalin's mother told him he would have done better to be a priest.