That's just my parents talking. (Post 22)

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As children, humans will formulate their beliefs and ideas largely based upon those held by their parents and those who are in frequent contact with them.  As a result, they have beliefs and ideas instilled within themselves by others before they are capable of making those decisions and judging the ethics of situations on their own.  This is both good and bad.  Most parents have their children's best interests in minds,and will typically try to do what they feel is in the child's best interests.  However, in some cases, parents have ideas that are detrimental to a society, and when those beliefs are passed down to further generations, there is greater reluctance for these values to be challenged and therefore changed. because the people holding the ideals have generally always felt them to be the correct way of thinking.  Looking at this phenomena biologically, there are neurological pathways, a repeatable sequence of neuron-firing, that is more commonly known as thought.  These pathways are much more easily formed (as they form canal-type pathways) at a younger age than later on in life.  Therefore, it is biologically harder to change thought later on in life, rather than at a young age when parents will typically have greater access to them than anyone else.

For comical representations of this, watch Brian in Season 4 Episode 4 (Don't make me over) of Family Guy, or Princess Clara in Season 1 Episode 1 of Drawn Together (Hot Tub) where both characters explain how their prejudices in their "adult" life were based upon prejudices held by their parents when they were young.