Even if they weren't born sociopaths, I think the process of blind obedience combined with ambitious ladder-climbing would have slowly killed off their consciences and their ability to have empathy for others - and by the time they reach apostle-hood, they've likely become a sociopath, IMO.
Sociopaths thrive in the business world - so it is not a stretch to think more than a few have thrived in Mormondom.