How do you account for those who are condescending/pompous/arrogant/conceited braggarts? Did they become that all by themselves or were they brainwashed to be precisely that by their parents?
How does one teach their children humility? Does they simply tell their child, "be humble"? No; humility is one of those things that must be taught by example. So does that mean if the parents are humble (in actions and words) that their children will automatically be humble as well (or vise versa)? No. No more than saying that if the parents never drank that their kids will never become alcoholics. it might give them an edge, but it's no guarantee. Personality type plays a lot with this. However, some personality types are more prone to exhibiting arrogant behaviors than others. For example an extrovert might seem more arrogant than an introvert. {This does not mean that all extroverts are arrogant or that all introverts are humble!} Everyone has an ego and when that ego is stroked it feels good (releases endorphins such as dopamine and serotonin in the brain .. but I won't go into that). Thusly, if one's ego is continuously stroked (be it by a parent, teacher ,friend, or whatever) that person may come to expect it (much like spoiling a child). {Again, this is not a certainty.}
No one is brainwashed into being arrogant. Everyone can resist being arrogant (although for some it may be very, very hard and others don't want to put forth the effort). Many people who are arrogant don't see themselves that way. They see themselves as deserving or being owed "whatever". Arrogance is blinding (thus the proverb, "Pride goes before destruction, and haughtiness before a fall).