For example - someone who grows up having experienced a negative situation with a particular group of people....

Exactly. Beliefs can change, once there is more evidence or lack of evidence to support them. They should change. Mine have changed since childhood, but are fundamental at the core on what they are - like the value of a human.

Older generations discount the lives of the young - the young discount the previous lives of the older. Neither can learn from the other - but there is less for an older person to learn from the young, than the young from the old. Learning happens in the positive and negative aspects of course - learn from other's mistakes, as well as their successes.