An interesting recent lecture by Dr. Joe Dispenza. There are so many theories out there. Western medicine will say it is either upbringing/environmental factors or genetics or a product of both. Traditional religion (Christianity) will say sometimes it is nature sometimes nurture, and sometimes there are dark forces at work. The Spiritual community seems split. Some believe in what Joe Dispenza discusses (darker forces) while others say there is no evil, and we incarnate with certain traits or life paths that sometimes is an unscrupulous one.