I think it can be a bit of both. Parents can be involved in conflict or family taboos can result in a variety of mental states in children growing up, one of them being self loathing. A person who blames themselves for an event happening during their childhood often is conditioned to think like that their entire life, or weaker minded people who are bullied and taken advantage of through most of their development (childhood, teenage years..). However, I think some societies can be bad juju with people still.
Take super introverted societies, Japan for example, where it is culturally appropriate to keep to yourself and not cause any scene. This can sometimes cause people to feel insignificant if they have an issue and nobody to speak to, and can explain a lot of the countries suicide statistics. People there do not say 'thank you' when complimented, they usually say 'No, I'm not' and are highly modest.
In another light, take a country like Iran or a lot of middle eastern areas where the population is almost 100% muslim. Extremist activities can lead women and female children to feel vulnerable and take on self loathing, but I don't think this can apply to many cows because not many, if any, are from extremist muslim areas lol
The fat fucks can be explained easy tho (inb4 ambylinnys), they're just miserable because they're the size of a car and are aware of it.