I think it has something to do with underdeveloped brain stems. Like babies born addicted to crack, many mothers "used" the drug of laziness and dependence which affected the in-utero development similarly. Tragic, really.
.....coupled with copious amounts of liberal indoctrination in public schools and universities..............mixed well with 'everybody else but me', lack of integrity and faith and moral foundation, well we can't help but wind up with The Left moonbats!!